Posts by Jai Ganesh

Jai Ganesh · This is Cool

Periodic Table

Gist

The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows ("periods") and columns ("groups"). An icon of chemistry, the periodic table is widely used in physics and other sciences.

The periodic table consists of 118 officially recognized elements, organized by atomic number, name, and symbol. Elements are ordered by increasing proton count, with symbols often matching the English name (e.g., Helium, He) or Latin roots (e.g., Gold, Au). Key groupings include metals, non-metals, halogens, and noble gases.

Summary

The periodic table of elements is widely used in the field of Chemistry to look up chemical elements as they are arranged in a manner that displays periodic trends in the chemical properties of the elements. However, the Periodic table generally displays only the symbol of the element and not its entire name.

Most of the symbols are similar to the name of the element but some symbols of elements have Latin roots. An example for this is silver which is denoted by Ag from its Latin name “Argentum”. Another such example would be the symbol ‘Fe’ which is used to denote Iron and can be traced to the Latin word for iron, “Ferrum”. It could prove difficult for a beginner in chemistry to learn the names of all the elements in the periodic table because these symbols do not always correspond to the English names of the elements.

Frequently Asked Questions – FAQs

Q1: What is the atomic number?
A1: The atomic number of an atom is equivalent to the total number of electrons present in a neutral atom or the total number of protons present in the nucleus of an atom.

Q2: What is an element?
A2. An element is a substance that can not be decomposed into simpler substances by ordinary chemical processes. It is the fundamental unit of the matter.

Q3: How many elements are there in the modern periodic table?
A3: There is a total of 118 elements present in the modern periodic table.

Q4: What is a chemical symbol?
A cA4: hemical symbol is a notation of one or two letters denoting a chemical element.
Example: The symbol of chlorine is Cl.

Q5: What are the rules for chemical symbols?
A5. The first letter is always capitalised for writing the chemical symbol of an element, while the second letter is small.

Q6: What is the significance of chemical symbols?
A6: Chemical symbols play a crucial role in easing the writing. It is universal, i.e. identical throughout the world.

Q7: What is the chemical symbol of a sodium metal?
A7: The chemical symbol of sodium metal is Na.

Q8: Name the smallest and the largest atom.
A8: Helium is the smallest atom with a radius of 31 pm, while the caesium is the largest atom with a radius of 298 pm.

Q9: Can atoms exist without neutrons?
A9: Yes, there is an isotope of the hydrogen atom, protium, which has no neutron.

Q10: What is the chemical symbol of a gold metal?
A10: The chemical symbol of gold metal is Au.

Details

The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows ("periods") and columns ("groups"). An icon of chemistry, the periodic table is widely used in physics and other sciences. It is a depiction of the periodic law, which states that when the elements are arranged in order of their atomic numbers an approximate recurrence of their properties is evident. The table is divided into four roughly rectangular areas called blocks. Elements in the same group tend to show similar chemical characteristics.

Vertical, horizontal and diagonal trends characterize the periodic table. Metallic character increases going down a group and from right to left across a period. Nonmetallic character increases going from the bottom left of the periodic table to the top right.

The first periodic table to become generally accepted was that of the Russian chemist Dmitri Mendeleev in 1869; he formulated the periodic law as a dependence of chemical properties on atomic mass. As not all elements were then known, there were gaps in his periodic table, and Mendeleev successfully used the periodic law to predict some properties of some of the missing elements. The periodic law was recognized as a fundamental discovery in the late 19th century. It was explained early in the 20th century, with the discovery of atomic numbers and associated pioneering work in quantum mechanics, both ideas serving to illuminate the internal structure of the atom. A recognisably modern form of the table was reached in 1945 with Glenn T. Seaborg's discovery that the actinides were in fact f-block rather than d-block elements. The periodic table and law have become a central and indispensable part of modern chemistry.

The periodic table continues to evolve with the progress of science. In nature, only elements up to atomic number 94 exist; elements beyond that can only be synthesized in the laboratory. By 2010, the first 118 elements were known, thereby completing the first seven rows of the table; however, chemical characterization is still needed for the heaviest elements to confirm that their properties match their positions. New discoveries will extend the table beyond these seven rows, though it is not yet known how many more elements are possible; moreover, theoretical calculations suggest that this unknown region will not follow the patterns of the known part of the table. Some scientific discussion also continues regarding whether some elements are correctly positioned in the table. Many alternative representations of the periodic law exist, and there is some discussion as to whether there is an optimal form of the periodic table.

Each chemical element has a unique atomic number (Z— for "Zahl", German for "number") representing the number of protons in its nucleus. Each distinct atomic number therefore corresponds to a class of atom: these classes are called the chemical elements. The chemical elements are what the periodic table classifies and organizes. Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on. Each of these names can be further abbreviated by a one- or two-letter chemical symbol; those for hydrogen, helium, and lithium are respectively H, He, and Li. Neutrons do not affect the atom's chemical identity, but do affect its weight. Atoms with the same number of protons but different numbers of neutrons are called isotopes of the same chemical element. Naturally occurring elements usually occur as mixes of different isotopes; since each isotope usually occurs with a characteristic abundance, naturally occurring elements have well-defined atomic weights, defined as the average mass of a naturally occurring atom of that element. All elements have multiple isotopes, variants with the same number of protons but different numbers of neutrons. For example, carbon has three naturally occurring isotopes: all of its atoms have six protons and most have six neutrons as well, but about one per cent have seven neutrons, and a very small fraction have eight neutrons. Isotopes are never separated in the periodic table; they are always grouped together under a single element. When atomic mass is shown, it is usually the weighted average of naturally occurring isotopes; but if no isotopes occur naturally in significant quantities, the mass of the most stable isotope usually appears, often in parentheses.

In the standard periodic table, the elements are listed in order of increasing atomic number. A new row (period) is started when a new electron shell has its first electron. Columns (groups) are determined by the electron configuration of the atom; elements with the same number of electrons in a particular subshell fall into the same columns (e.g. oxygen, sulfur, and selenium are in the same column because they all have four electrons in the outermost p-subshell). Elements with similar chemical properties generally fall into the same group in the periodic table, although in the f-block, and to some respect in the d-block, the elements in the same period tend to have similar properties, as well. Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it.

Today, 118 elements are known, the first 94 of which are known to occur naturally on Earth. The remaining 24, americium to oganesson (95–118), occur only when synthesized in laboratories. Of the 94 naturally occurring elements, 83 are primordial and 11 occur only in decay chains of primordial elements. A few of the latter are so rare that they were not discovered in nature, but were synthesized in the laboratory before it was determined that they exist in nature: technetium (element 43), promethium (element 61), astatine (element 85), neptunium (element 93), and plutonium (element 94). No element heavier than einsteinium (element 99) has ever been observed in macroscopic quantities in its pure form, nor has astatine; francium (element 87) has been only photographed in the form of light emitted from microscopic quantities. Of the 94 natural elements, eighty have a stable isotope and one more (bismuth) has an almost-stable isotope (with a half-life of 2.01×{10}^{19} years, over a billion times the age of the universe). Two more, thorium and uranium, have isotopes undergoing radioactive decay with a half-life comparable to the age of the Earth. The stable elements plus bismuth, thorium, and uranium make up the 83 primordial elements that survived from the Earth's formation. The remaining eleven natural elements decay quickly enough that their continued trace occurrence rests primarily on being constantly regenerated as intermediate products of the decay of thorium and uranium.[d] All 24 known artificial elements are radioactive.

Group names and numbers

Under an international naming convention, the groups are numbered numerically from 1 to 18 from the leftmost column (the alkali metals) to the rightmost column (the noble gases). The f-block groups are ignored in this numbering. Groups can also be named by their first element, e.g. the "scandium group" for group 3. Previously, groups were known by Roman numerals. In the United States, the Roman numerals were followed by either an "A" (if the group was in the s- or p-block) or a "B" (if the group was in the d-block). The Roman numerals used correspond to the last digit of today's naming convention (e.g., the group 4 elements were group IVB, and the group 14 elements were group IVA). In Europe, "A" was used for groups 1 through 7, and "B" was used for groups 11 through 17. In addition, groups 8, 9, and 10 used to be treated as one triple-sized group, known collectively in both notations as group VIII. In 1988, the new IUPAC (International Union of Pure and Applied Chemistry) naming system (1–18) was put into use, and the old group names (I–VIII) were deprecated.

Additional Information

Periodic table, in chemistry, is the organized array of all the chemical elements in order of increasing atomic number—i.e., the total number of protons in the atomic nucleus. When the chemical elements are thus arranged, there is a recurring pattern called the “periodic law” in their properties, in which elements in the same column (group) have similar properties. The initial discovery of this pattern by Dmitri I. Mendeleev in the mid-19th century has been of inestimable value in the development of chemistry.

It was not recognized until the 1910s that the order of elements in the periodic system is that of their atomic numbers, which are equal to the positive electrical charges of the atomic nuclei expressed in electronic units. In subsequent years great progress was made in explaining the periodic law in terms of the electronic structure of atoms and molecules. This clarification has increased the value of the law, which is used as much today as it was at the beginning of the 20th century, when it expressed the only known relationship among the elements.

The periodic table

The periodic table of the elements contains all of the chemical elements that have been discovered or made; they are arranged, in the order of their atomic numbers, in seven horizontal periods, with the lanthanoids (lanthanum, 57, to lutetium, 71) and the actinoids (actinium, 89, to lawrencium, 103) indicated separately below. The periods are of varying lengths. First there is the hydrogen period, consisting of the two elements hydrogen, 1, and helium, 2. Then there are two periods of eight elements each: the first short period, from lithium, 3, to neon, 10, and the second short period, from sodium, 11, to argon, 18. There follow two periods of 18 elements each: the first long period, from potassium, 19, to krypton, 36, and the second long period, from rubidium, 37, to xenon, 54. The first very long period of 32 elements, from cesium, 55, to radon, 86, is condensed into 18 columns by the omission of the lanthanoids (which are indicated separately below), permitting the remaining 18 elements, which are closely similar in their properties to corresponding elements of the first and second long periods, to be placed directly below these elements. The second very long period, from francium, 87, to oganesson, 118, is likewise condensed into 18 columns by the omission of the actinoids.

Groups

The six noble gases—helium, neon, argon, krypton, xenon, and radon—occur at the ends of the six completed periods and constitute the Group 18 (0) group of the periodic system. It is customary to refer to horizontal series of elements in the table as periods and vertical series as groups. The seven elements lithium to fluorine and the seven corresponding elements sodium to chlorine are placed in the seven groups, 1 (Ia), 2 (IIa), 13 (IIIa), 14 (IVa), 15 (Va), 16 (VIa), and 17 (VIIa), respectively. The 17 elements of the fourth period, from potassium, 19, to bromine, 35, are distinct in their properties and are considered to constitute Groups 1–17 (Ia–VIIa) of the periodic system.

The first group, the alkali metals, thereby includes, in addition to lithium and sodium, the metals from potassium down the table to francium but not the much less similar metals of Group 11 (Ib; copper, etc.). Also the second group, the alkaline-earth metals, is considered to include beryllium, magnesium, calcium, strontium, barium, and radium but not the elements of Group 12 (IIb). The boron group includes those elements in Group 13 (IIIa). The other four groups are as follows: The carbon group, 14 (IVa), consists of carbon, silicon, germanium, tin, lead, and flerovium; the nitrogen group, 15 (Va), includes nitrogen, phosphorus, math, antimony, bismuth, and moscovium; the oxygen group, 16 (VIa), includes oxygen, sulfur, selenium, tellurium, polonium, and livermorium; and the halogen group, 17 (VIIa), includes fluorine, chlorine, bromine, iodine, astatine, and tennessine.

Although hydrogen is included in Group 1 (Ia), it is not closely similar to either the alkali metals or the halogens in its chemical properties. It is, however, assigned the oxidation number +1 in compounds such as hydrogen fluoride, HF, and −1 in compounds such as lithium hydride, LiH; and it may hence be considered as being similar to a Group 1 (Ia) element and to a Group 17 (VIIa) element, respectively, in compounds of these two types, taking the place first of Li and then of F in lithium fluoride, LiF. Hydrogen is, in fact, the most individualistic of the elements: No other element resembles it in the way that sodium resembles lithium, chlorine resembles fluorine, and neon resembles helium. It is a unique element, the only element that cannot conveniently be considered a member of a group.

A number of the elements of each long period are called the transition metals. These are usually taken to be scandium, 21, to zinc, 30 (the iron-group transition metals); yttrium, 39, to cadmium, 48 (the palladium-group transition metals); and hafnium, 72, to mercury, 80 (the platinum-group transition metals). By this definition, the transition metals include Groups 3 to 12 (IIIb to VIIIb, and Ib and IIb).

Periodic trends in properties

The periodicity in properties of the elements arranged in order of atomic number is strikingly shown by the consideration of the physical state of the elementary substances and such related properties as the melting point, density, and hardness. The elements of Group 18 (0) are gases that are difficult to condense. The alkali metals, in Group 1 (Ia), are soft metallic solids with low melting points. The alkaline-earth metals, in Group 2 (IIa), are harder and have higher melting points than the adjacent alkali metals. The hardness and melting point continue to increase through Groups 13 (IIIa) and 14 (IVa) and then decrease through Groups 15 (Va), 16 (VIa), and 17 (VIIa). The elements of the long periods show a gradual increase in hardness and melting point from the beginning alkali metals to near the center of the period and then at Group 16 (VIa) an irregular decrease to the halogens and noble gases.

The valence of the elements (that is, the number of bonds formed with a standard element) is closely correlated with position in the periodic table, the elements in the main groups having maximum positive valence, or oxidation number, equal to the group number and maximum negative valence equal to the difference between eight and the group number.

Metallic elements in the periodic table

The general chemical properties described as metallic or base forming, metalloid or amphoteric, and nonmetallic or acid forming are correlated with the periodic table in a simple way: The most metallic elements are to the left and to the bottom of the periodic table and the most nonmetallic elements are to the right and to the top (ignoring the noble gases). The metalloids are adjacent to a diagonal line from boron to polonium.

A closely related property is electronegativity, the tendency of atoms to retain their electrons and to attract additional electrons. The degree of electronegativity of an element is shown by ionization potential, electron affinity, oxidation-reduction potential, the energy of formation of chemical bonds, and other properties. It is shown to depend upon the element’s position in the periodic table in the same way that nonmetallic character does, fluorine being the most electronegative element and cesium (or francium) the least electronegative (most electropositive) element.

The sizes of atoms of elements vary regularly throughout the periodic system. Thus, the effective bonding radius (or one-half the distance between adjacent atoms) in the elementary substances in their crystalline or molecular forms decreases through the first short period from 1.52 Å for lithium to 0.73 Å for fluorine; at the beginning of the second period, the bonding radius rises abruptly to 1.86 Å for sodium and gradually decreases to 0.99 Å for chlorine. The behavior through the long periods is more complex: The bonding radius decreases gradually from 2.31 Å for potassium to a minimum of 1.25 Å for cobalt and nickel, then rises slightly, and finally falls to 1.14 Å for bromine. The sizes of atoms are of importance in the determination of coordination number (that is, the number of groups attached to the central atom in a compound) and hence in the composition of compounds.

The increase in atomic size from the upper right corner of the periodic table to the lower left corner is reflected in the formulas of the oxygen acids of the elements in their highest states of oxidation. The smallest atoms group only three oxygen atoms about themselves; the next larger atoms, which coordinate a tetrahedron of four oxygen atoms, are in a diagonal belt; and the still larger atoms, which form octahedral oxygen complexes (stannic acid, antimonic acid, telluric acid, paraperiodic acid), lie below and to the left of this belt. Only the chemical and physical properties of the elements are determined by the extranuclear electronic structure; these properties show the periodicity described in the periodic law. The properties of the atomic nuclei themselves, such as the magnitude of the packing fraction and the power of entering into nuclear reactions, are, although dependent upon the atomic number, not dependent in the same periodic way.

The basis of the periodic system:

Electronic Structure

The noble gases—helium, neon, argon, krypton, xenon, radon, and oganesson—have the striking chemical property of forming few chemical compounds. This property would depend upon their possessing especially stable electronic structures (that is, structures so firmly knit that they would not yield to accommodate ordinary chemical bonds). During the development of modern atomic physics and the theory of quantum mechanics, a precise and detailed understanding was obtained of the electronic structure of the noble gases and other atoms that explains the periodic law in a thoroughly satisfactory manner.

The Pauli exclusion principle states that no more than two electrons can occupy the same orbit—or, in quantum-mechanical language, orbital—in an atom and that two electrons in the same orbital must be paired (that is, must have their spins opposed, with one spin up and one spin down). The orbitals in an atom may be described by a principal quantum number, n, which may assume the values 1, 2, 3,…, and by an azimuthal quantum number, l, which may assume the values 0, 1, 2,…, n − 1. There are 2l + 1 distinct orbitals for each set of values of n and l.

The most stable orbitals, which bring the electron closest to the nucleus, are those with the smallest values of n and l. The electrons that occupy the orbital with n = 1 (and l = 0) are said to be in the K shell of electrons; the L, M, N,… shells correspond respectively to n = 2, 3, 4,…. Each shell except the K shell is divided into subshells corresponding to the values 0, 1, 2, 3,… of the orbital quantum number l; these subshells are called the s, p, d, and f subshells, and they can accommodate a maximum of 2, 6, 10, and 14 electrons, respectively. (There is no special significance to the letter designations of the quantum numbers or of the shells and subshells.)

The approximate order of stability of the successive subshells in an atom is indicated in the chart below. The number of electrons in the atoms of the elements increases with increasing atomic number, and the added electrons go, of necessity, into successively less stable shells. The most stable shell, the K shell, is completed with helium, which has two electrons. The L shell is then completely filled at neon, with atomic number 10. The atoms of the heavier noble gases do not, however, have a completed outer shell but instead have s and p subshells only. The outer shell of eight electrons is called traditionally an octet. The d subshells and f subshells subsequently are also filled with electrons after the initially less stable orbitals are occupied, an inversion of stability having occurred with increasing atomic number.

The numbers 2, 8, 18, and 32 correspond to filling the s; s and p; s, p, and d; and s, p, d, and f subshells, respectively. The elements in groups 13 through 18 (with the exception of helium) are called p-block elements because in those elements, the p subshells are being filled across the periods.

The first period of the periodic table is complete at helium, when the K shell is filled with two electrons. The first and second short periods represent the filling of the 2s and 2p subshells (completing the L shell at neon) and the 3s and 3p subshells (at argon), leaving the M shell incomplete. The first long period begins with the introduction of electrons into the 4s orbital. Then, at scandium, the five 3d orbitals of the inner M shell begin to be occupied. It is the successive occupancy of these five 3d orbitals by their complement of ten electrons that characterizes the ten elements of the iron-group transition series. At krypton the M shell is complete and there is an octet in the N shell. The second long period, of 18 elements, similarly represents the completion of an outer octet and the next inner subshell of ten 4d electrons.

The very long period of 32 elements results from the completion of the 4f subshell of 14 electrons, the 5d subshell of 10 electrons, and the 6s, 6p octet. The filling of the 4f orbitals corresponds to the sequence of 14 lanthanoids and that of the 5d orbitals to the 10 platinum-group transition metals.

The next period involves the 5f subshell of 14 electrons, the 6d subshell of 10 electrons, and the 7s, 7p octet. The filling of the 5f orbitals corresponds to the actinoids, the elements beginning with thorium, atomic number 90.

There are advantages to replacing the K, L, M,… shells by a different grouping of the subshells, in which those with nearly the same energy are grouped together, in close correlation with the periodic system.

The periodicity of properties of the elements is caused by the periodicity in electronic structure. The noble gases are chemically unreactive, or nearly so, because their electronic structures are stable—their atoms hold their quota of electrons strongly, have no affinity for more electrons, and have little tendency to share electrons with other atoms. An element close to a noble gas in the periodic system, on the other hand, is reactive chemically because of the possibility of assuming the stable electronic configuration of the noble gas, by losing one or more electrons to another atom, by gaining one or more electrons from another atom, or by sharing electrons. The alkali metals, in Group 1 (Ia), can assume the noble-gas configuration by losing one electron, which is loosely held in the outermost (valence) shell, to another element with greater electron affinity, thus producing the stable singly charged positive ions. Similarly the alkaline-earth metals can form doubly charged positive ions with the noble-gas electronic configuration by losing the two loosely held electrons of the valence shell; the positive ionic valences of the elements of the first groups are hence equal to the group numbers. The elements just preceding the noble gases can form negative ions with the noble-gas configuration by gaining electrons; the negative ionic valences of these elements are equal to the difference between eight and their group numbers. The covalence (or number of shared electron pairs) of an atom is determined by its electron number and the stable orbitals available to it. An atom such as fluorine, with seven electrons in its outer shell, can combine with a similar atom by sharing a pair of electrons with it; each atom thus achieves the noble-gas configuration by having three unshared pairs and one shared electron pair in its valence shell.

The properties of elements in the same group of the periodic system are, although similar, not identical. The trend in properties from the lighter to the heavier elements may be attributed to changes in the strength of binding of the outer electrons and especially to the increasing size of the atoms.

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Jai Ganesh · This is Cool

2531) Manganese Dioxide

Gist

Manganese dioxide (MnO2) is a black or brown inorganic compound occurring naturally as the mineral pyrolusite, which is the main ore of manganese. It is primarily used as a cathodic depolarizer in dry-cell batteries, a catalyst for oxygen production, and as a pigment in ceramics and glass. It is a strong oxidizing agent.

Manganese dioxide (MnO2) is a versatile inorganic compound primarily used as a depolarizer in dry cell (alkaline) batteries, a powerful oxidant in chemical synthesis, and a catalyst for producing oxygen. It is widely used in ceramics, glass decolorization, water purification, and as a raw material for producing manganese steel.

Summary:

Manganese dioxide (Mn02) is a highly versatile compound that is used for water treatment, water softening, iron removal, and other industrial manufacturing processes. Manganese dioxide is an indispensable organic compound for diverse applications across different sectors.

What is Manganese Dioxide?

Manganese Dioxide Chemical Formula: Mn02 : Manganese dioxide is an inorganic compound with the chemical formula Mn02. It is a black or brown-coloured material that naturally occurs as mineral pyrolusite. It is extensively used in different industries for its unique physical and chemical properties. Manganese dioxide is primarily used in groundwater applications. It effectively removes hydrogen sulfide, manganese radium, and iron from water.

What are the Uses of Managese Dioxide?

It finds application in different industries for its excellent chemical and physical properties. The following are the main uses of manganese dioxide.

Application of Manganese Dioxide

* Oxidizing Agent: One of the main uses of manganese dioxide is oxidizing agent. It oxidizes different chemicals and compounds that are essential in the production of batteries. Manganese dioxide is used as a depolarizer in dry-cell batteries to convert gas into water and generate energy.
* Catalyst: It is one of the most powerful catalysts for water treatment. It acts as a filtration agent for water. The catalyst reaction by manganese dioxide during the chemical oxidation reduction process helps to remove math, iron, and radium.
* Production of Ceramic Materials: They are used as a colouring agent to add brown and black pigments to ceramic glazes. They are also used in manufacturing clay to enhance strength and durability.
* Decolouring Agent:Manganese dioxide is used as the decolouring agent in glass production and an oxidizing agent in a chemical agent.
* Steel Production:It is used in the production of steel and other alloys. Mn02 is added to iron during the manufacturing process to remove impurities and improve the quality of the end product.
* Medical Research: Manganese dioxide nanomaterials are explored for drug delivery in cancer therapy.

Details:

What is Manganese dioxide?

* Manganese dioxide is a black-brown solid that occurs naturally with the formula MnO2.
* Manganese dioxide (MnO2), known as pyrolusite when found in nature, is the most plentiful of all the manganese compounds.
* The principal ore of manganese dioxide is pyrolusite which was known to the ancients as a pigment.

Impure manganese can be made by reducing manganese dioxide with carbon. It is the only important compound of quadripositive manganese.

When MnO2 is fused with KOH

When blackish coloured compound MnO2 is fused with KOH in presence of air, it produces a dark green coloured compound potassium manganate.

Uses of Manganese dioxide – MnO2

* Used in Ceramic Industries for making glass, practically all the raw materials used in glass contain some iron, usually in the form of ferric oxide.
* Ores of manganese are not ‘active’ for direct use in dry cell manufacture and many of them need to be activated by physical or chemical treatment.
* Used in glassmaking to remove the green tint caused by iron impurities.
* Used as an important component in batteries. In the Leclanche cell, the positive electrode carbon, is surrounded by manganese dioxide and carbon.

Frequently Asked Questions – FAQs

Q1: What are the uses of manganese dioxide?
A1: MnO2 is primarily used as a part of dry cell batteries: alkaline batteries and the so-called Leclanché cell, or zinc–carbon batteries. For this application, large quantity are consumed annually. Many industrial uses include the use of MnO2 in ceramics and glass-making as an inorganic pigment.

Q2: Is MnO2 a catalyst?
A2: Manganese dioxide, a compound with the formula MnO2, is used as a catalyst for rapid oxidation of dissolved iron and manganese, present in the form of ferrous and manganese powder, in contact filters. These salts are oxidised by dissolved oxygen to an insoluble ferric and manganic acid.

Q3: How is manganese dioxide formed?
A3: By oxidation of the elemental manganese: elemental manganese reacts with oxygen in the environment to form MnO2. Because of this reaction, elemental manganese does not exist in nature – it is usually found as manganese dioxide in nature.

Q4: Is manganese dioxide harmful to humans?
A4: Harmful if inhaled or swallowed. It may cause eye, skin, and respiratory tract irritation. May cause central nervous system effects. Inhalation of fumes may cause metal-fume fever.

Q5: What are the symptoms of manganese toxicity?
A5: Manganese toxicity can result in a permanent neurological disorder known as manganism with symptoms that include tremors, difficulty walking, and facial muscle spasms. These symptoms are often preceded by other lesser symptoms, including irritability, aggressiveness, and hallucinations.

Additional Information

Manganese dioxide is the inorganic compound with the formula MnO2. This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for MnO2 is for dry-cell batteries, such as the alkaline battery and the zinc–carbon battery, although it is also used for other battery chemistries such as aqueous zinc-ion batteries. MnO2 is also used as a pigment and as a precursor to other manganese compounds, such as potassium permanganate (KMnO4). It is used as a reagent in organic synthesis, for example, for the oxidation of allylic alcohols. MnO2 has an α-polymorph that can incorporate a variety of atoms (as well as water molecules) in the "tunnels" or "channels" between the manganese oxide octahedra.

Key uses of manganese dioxide include:

Battery Manufacturing: It is a key ingredient (depolarizer) in Zinc-carbon (Leclanché) and alkaline batteries.
Water Treatment: Used for removing iron, manganese, and hydrogen sulfide from water supplies.
Catalyst: Functions as a catalyst in chemical processes, such as the decomposition of hydrogen peroxide and in producing oxygen.
Ceramics and Glass: Used as a colorant to create black or brown pigments and to remove the green tint from glass caused by iron impurities.
Chemical Synthesis: Acts as an oxidizing agent for producing aromatic chemicals and in various organic syntheses.
Other Applications: Employed in the production of fireworks, agricultural fungicides/pesticides, and in paints as a drying agent.

Jai Ganesh · Dark Discussions at Cafe Infinity

2468) Otto Diels

Gist:

Work

The element carbon is the component in a large and varied family of chemical compounds—organic compounds. Diens are compounds of carbon and hydrogen that contain two double bonds, i.e., where two carbon atoms share two pairs of paired electrons. In 1928 Otto Diels and Kurt Alder discovered a reaction in which one dien was changed into a ring-shaped molecule with six carbon atoms. The reaction became very significant within the chemical industry. For example, it served as a link in the production of plastic and synthetic rubber.

Summary

Otto Paul Hermann Diels (born Jan. 23, 1876, Hamburg, Ger.—died March 7, 1954, Kiel, W.Ger.) was a German organic chemist who, with Kurt Alder, was awarded the Nobel Prize for Chemistry in 1950 for their joint work in developing a method of preparing cyclic organic compounds.

Diels studied chemistry at the University of Berlin under Emil Fischer and after various appointments was made professor of chemistry at the University of Kiel (1916). He became emeritus in 1945.

In 1906 Diels discovered a highly reactive substance, carbon suboxide (the acid anhydride of malonic acid), and determined its properties and chemical composition. He also devised an easily controlled method of removing some of the hydrogen atoms from certain organic molecules by the use of metallic selenium.

His most important work concerned the diene synthesis, in which organic compounds with two carbon-to-carbon double bonds were used to effect syntheses of many cyclic organic substances under conditions that threw light on the molecular structure of the products obtained. This method was developed (1928) in collaboration with Kurt Alder, his student, and is known as the Diels-Alder reaction. Their work proved especially important in the production of synthetic rubber and plastics.

Details

Otto Paul Hermann Diels (23 January 1876 – 7 March 1954) was a German chemist. His most notable work was done with Kurt Alder on the Diels–Alder reaction, a method for cyclohexene synthesis. The pair was awarded the Nobel Prize in Chemistry in 1950 for their work. Their method of synthesizing cyclic organic compounds proved valuable for the manufacture of synthetic rubber and plastic. He completed his education at the University of Berlin, where he later worked. Diels was employed at the University of Kiel when he completed his Nobel Prize-winning work, and remained there until he retired in 1945. Diels was married, with five children. He died in 1954. He was survived by all five of his children and his wife.

Early life

Diels was born on 23 January 1876 in Hamburg, Germany, and moved with his family to Berlin when he was two years old. He studied in Berlin at Joachimsthalsches Gymnasium before attending the University of Berlin starting in 1895. While at university, Diels studied chemistry under Emil Fischer, eventually graduating in 1899.

Professional career

Immediately after graduating from the University of Berlin, he was offered a position with the Institute of Chemistry at the school. He advanced quickly through the ranks at the school, eventually ending up as Department Head in 1913. He remained at the University of Berlin until 1915, when he accepted a position at the University of Kiel, where he remained until his retirement in 1945. It was during his time at Kiel, where he worked with Kurt Alder developing the Diels–Alder reaction, for which they were awarded the Nobel Prize in Chemistry in 1950. His work with Alder developed a synthetic method which allows the synthesis of unsaturated cyclic compounds. This work was important in the production of synthetic rubber and plastic compounds.

Personal life

Diels married Paula Geyer in 1909. The couple had five children together, three sons and two daughters. Two of his sons were killed in action during World War II. In his free time, Diels enjoyed reading, music and traveling. He died on 7 March 1954.

Jai Ganesh · Dark Discussions at Cafe Infinity

Comfortable Quotes - IV

1. I've always been at war with myself, for right or wrong. I don't know how to explain it more. It's universal. Some people are better at dealing with it, and they sleep with no pain - not pain, arguments. I've grown quite comfortable with being at war. - Brad Pitt

2. I just knew that there was a gap in the market for easy, comfortable garments that are neither luxury nor pret, but somewhere in between. - Masaba Gupta

3. When you're comfortable with someone you love, the silence is the best. And, that's how me and J. are. When we're in a room together, we don't have to say anything. It's for real. - Britney Spears

4. It does not seem to me that the steps which would be needed to make Britain - and others - more comfortable in their relationship in the European Union are inherently so outlandish or unreasonable. - David Cameron

5. I'm learning that you can be comfortable and still look beautiful. - Selena Gomez

6. I like a good pair of jeans, but I also like putting on a nice tux. I'd rather go around in a good pair of jeans that you don't wash every day, because they get more and more comfortable. - Matthew McConaughey

7. A broken heart is a very pleasant complaint for a man in London if he has a comfortable income. - George Bernard Shaw

8. This game can be brutal. As soon as you get comfortable, it bites you. You have to stay on it all the time. - Joe Root.

Jai Ganesh · Jokes

Q: Why did the fruit bat eat the orange?
A: Because it had appeal.
* * *
Q: What do you call a fruit riding a motorcycle?
A: An Orange County Chopper.
* * *
Q: Why did the man lose his job at the orange juice factory?
A: He couldn't concentrate!
* * *
I thought I was drowning in Crush soda, but it was only a Fanta sea.
* * *
Knock Knock!
Who's there?
Orange.
Orange who?
Orange you going to answer the door?
* * *

Jai Ganesh · This is Cool

Cardiopulmonary Resuscitation (CPR)

Gist

Cardiopulmonary Resuscitation (CPR) is an emergency procedure for someone who is unresponsive and not breathing normally. It involves 30 chest compressions (100-120 per minute) followed by 2 rescue breaths (or continuous "hands-only" compressions) to keep blood flowing to vital organs until professional help arrives.

The 7 steps of CPR (Cardiopulmonary Resuscitation) involve ensuring scene safety, checking responsiveness, calling emergency services, opening the airway, checking for breathing, performing 30 chest compressions, and delivering 2 rescue breaths. These steps are repeated until medical help arrives or the patient wakes up.

Summary

Cardiopulmonary resuscitation (CPR) is an emergency procedure used during cardiac or respiratory arrest that involves chest compressions, often combined with artificial ventilation, to preserve brain function and maintain circulation until spontaneous breathing and heartbeat can be restored. It is recommended for those who are unresponsive with no breathing or abnormal breathing, for example, agonal respirations.

CPR involves chest compressions for adults between 5 cm (2.0 in) and 6 cm (2.4 in) deep and at a rate of at least 100 to 120 per minute. The rescuer may also provide artificial ventilation by either exhaling air into the subject's mouth or nose (mouth-to-mouth resuscitation) or using a device that pushes air into the subject's lungs (mechanical ventilation). Current recommendations emphasize early and high-quality chest compressions over artificial ventilation; a simplified CPR method involving only chest compressions is recommended for untrained rescuers. With children, however, 2015 American Heart Association guidelines indicate that doing only compressions may result in worse outcomes, because such problems in children normally arise from respiratory issues rather than from cardiac ones, given their young age. Chest compression to breathing ratios are set at 30 to 2 in adults.

CPR alone is unlikely to restart the heart. Its main purpose is to restore the partial flow of oxygenated blood to the brain and heart. The objective is to delay tissue death and to extend the brief window of opportunity for a successful resuscitation without permanent brain damage. Administration of an electric shock to the subject's heart, termed defibrillation, is usually needed to restore a viable, or "perfusing", heart rhythm. Defibrillation is effective only for certain heart rhythms, namely ventricular fibrillation or pulseless ventricular tachycardia, rather than asystole or pulseless electrical activity, which usually requires the treatment of underlying conditions to restore cardiac function. Early shock, when appropriate, is recommended. CPR may succeed in inducing a heart rhythm that may be shockable. In general, CPR is continued until the person has a return of spontaneous circulation (ROSC) or is declared dead.

Medical uses

CPR is indicated for any person unresponsive with no breathing or breathing only in occasional agonal gasps, as it is most likely that they are in cardiac arrest. If a person still has a pulse but is not breathing (respiratory arrest), artificial ventilations may be more appropriate, but due to the difficulty people have in accurately assessing the presence or absence of a pulse, CPR guidelines recommend that lay persons should not be instructed to check the pulse while giving healthcare professionals the option to check a pulse. In those with cardiac arrest due to trauma, CPR is considered futile but still recommended. Correcting the underlying cause such as a tension pneumothorax or pericardial tamponade may help.

Details

CPR (cardiopulmonary resuscitation) is an emergency procedure for someone who’s in cardiac arrest. CPR with breaths and hands-only CPR are the two types. Even if you’re not CPR-certified, you can do hands-only CPR. This involves doing 100 to 120 chest compressions per minute. Start CPR immediately to give the person the best chance of survival.

What Is CPR?

CPR stands for cardiopulmonary resuscitation. It’s an emergency procedure that can save your life if you’re in cardiac arrest. This means your heart stops beating and can’t pump blood out to your body. The key part of CPR is chest compressions (pushing hard and fast in the center of the chest). This keeps some blood flowing to vital organs. CPR may also involve mouth-to-mouth breaths, which give you oxygen.

Healthcare providers, like doctors, nurses and paramedics, routinely perform CPR both in and out of hospitals. Others, called lay rescuers, can also perform CPR wherever it’s needed, like at homes, gyms and shopping malls.

If you’re reading this and aren’t a healthcare provider, you have the opportunity to be a lay rescuer. This means you can save someone’s life, no matter who you are. Lay rescuers include people with CPR certification (you take classes and get an official certificate), as well as those without it. You’ll do the type of CPR that reflects your training and comfort level.

Types of CPR

There are two main types of CPR:

* CPR with breaths (conventional CPR): You use chest compressions and mouth-to-mouth breaths. You need CPR certification to do this type.
* Hands-only CPR: You only use chest compressions (no breaths). You don’t need CPR certification to do this type. You can learn on your own.

Both types are effective and can be lifesaving within the first few minutes of cardiac arrest in adults. However, CPR with breaths is more helpful in situations where CPR must go on for longer than a few minutes. This is because the person’s blood needs more oxygen at that point to prevent damage to vital organs like the brain.

How to recognize when someone needs CPR

A person needs CPR if they’re unconscious and have absent or abnormal breathing. Here’s what that means:

* Unconscious: This is also called being “unresponsive.” It means the person doesn’t respond if you shout, say their name or tap them on the shoulder.
* Absent or abnormal breathing: This means the person either isn’t breathing, or they’re breathing in ways that don’t sound normal. It may sound like they’re gasping for air.

These are signs that the person is in cardiac arrest.

What not to do

When someone’s in cardiac arrest, do NOT delay CPR in order to:

* Check for a pulse: The latest guidelines say that lay rescuers should NOT check for a pulse (this is true even if you’re CPR certified). This can waste valuable time. If the person is unresponsive and not breathing right, start CPR right away.
* Check their airways for an object that’s stuck: The guidelines do NOT recommend routine inspection of the mouth or throat when a person is in cardiac arrest. Also, never do a “blind finger sweep,” looking for an object. This can push any object deeper into the airway.

The only time to check the airways for a lodged object is if you witness someone collapse while choking. In that case, quickly look in their mouth. Don’t feel around for an object. But if you can clearly see an object and it’s easily removed, you can remove it. Otherwise, start CPR right away.

Procedure Details

Before starting CPR, quickly ask someone to:

* Call your local emergency services number): Ideally, someone nearby can make the call so you can immediately start CPR. But if you’re alone, call for emergency help and put the phone on speaker while you get started.
8 Get an automated external defibrillator (AED): An AED is a device that can restart the heart. AEDs are available in many public places. You can use them even if you don’t have training. The device will give you instructions aloud.

It may take some minutes for emergency services to arrive and for someone to find an AED. Don’t wait. Start CPR immediately.

CPR steps for adults and teens

1. Make sure the person is on a firm, flat surface. They should be lying on their back. Gently position the person as needed.
2. Kneel down. You should be next to the person, with your knees about shoulder width apart.
3. Place your hands on their chest. Put the heel of one hand in the middle of their chest, with your fingers lifted upward and spread out. Put your other hand on top and interlace your fingers. Your fingers should be slightly lifted up off their chest, with the lower heel pressing down.
4. Position your body. Your shoulders should be directly over your hands. Your arms should extend straight downward, with your elbows locked (not bent). This helps you use your body weight to push down forcefully enough.
5. Start chest compressions. Push down on the middle of the person’s chest with hard, fast movements. Their chest should go down by at least 2 inches (5 centimeters) each time, but not more than 2.4 inches (6 centimeters). Their chest should rise up before you push again.
6. Keep a steady pace. Do chest compressions at a rate of 100 to 120 per minute. This follows the beat of “Stayin’ Alive,” by the Bee Gees, and “Crazy in Love,” by Beyoncé and Jay-Z. Make sure you allow the person’s chest to come all the way back up between compressions.
7. Give breaths (IF TRAINED). For hands-only CPR, simply continue doing chest compressions. But if you’re CPR certified and willing to give breaths, you should do so. Follow the guidance you learned in your training. You should generally give two breaths after every 30 compressions.

Continue doing CPR until any of the following happen:

* The person starts breathing normally again.
* First responders arrive and take over the care.
* An AED is available to use (if this happens, stop CPR and start using the AED right away).

If at any point, you feel too tired to continue, let someone else who’s ready step in. Make the switch as quickly as possible so there aren’t long breaks in between compressions. Generally, it’s advised to switch personnel every two minutes.

CPR steps for children and babies

There are some key differences when you’re doing CPR for anyone 12 or younger. Here’s what to know:

* CPR with breaths is best for children and babies. This means, ideally, someone who’s CPR certified will step in. But if no one with training is available, it’s OK to do hands-only CPR.
* For infants, don’t use both hands for chest compressions. Instead, use modified techniques that are more appropriate for an infant’s small size. These are described farther below. The infant’s chest should go down by about 1.5 inches (4 centimeters).
* For children, use either one or two hands for chest compressions. It depends on the size of the child. For children 1 to 8 years old, using one hand may be OK as long as you can keep the proper form. The child’s chest should go down by about 2 inches (5 centimeters).

When performing CPR on an infant (1 to 12 months old), use one of the following techniques for chest compressions:

* The “two thumb-encircling hands” technique: You wrap both hands around the infant’s upper body. Your thumbs should meet at the center of their chest, forming an upside-down V. Push down with both thumbs. This is better than doing two-finger compressions (an older method).
* The “heel-of-one-hand” technique: If you can’t wrap both hands around the infant, then use the heel of one hand (not both) to do chest compressions.

What are the potential benefits and risks of CPR?

CPR can save your life if you receive it right after going into cardiac arrest. CPR keeps blood moving through your body. This may prevent organ damage, like cerebral hypoxia.

Some people with certain preexisting health conditions might not experience the same benefits from CPR. It depends on how sick you are before you go into cardiac arrest. Consider speaking with a healthcare provider you trust about what your recovery or outlook might look like if you needed CPR.

Possible risks of CPR include broken ribs and injury to organs in your chest. This is because chest compressions must be forceful to keep blood circulating and keep you alive.

Recovery and Outlook:

What happens immediately after CPR?

If you’re a lay rescuer, you’ll step back when first responders arrive. They’ll take over and begin providing medical care. They’ll transport the person to a hospital as soon as possible. If the person survives, healthcare providers will check for any organ damage from a lack of oxygen. They’ll also determine the cause of cardiac arrest and provide any needed treatment.

If a cardiac arrest occurs at home and an individual wakes up after CPR from a non-trained family member, they should be evaluated immediately by a healthcare team. This is true even if they look well.

Additional Information

CPR stands for cardiopulmonary resuscitation. It can help save a life during cardiac arrest, when the heart stops beating or beats too ineffectively to circulate blood to the brain and other vital organs.

What Is the Purpose of CPR?

With a half-million cardiac arrests each year, CPR increases the likelihood of surviving cardiac arrest, when the heart stops beating or beats too ineffectively to circulate blood to the brain and other vital organs. It’s not just for healthcare workers and emergency responders. CPR can double or triple the chance of survival when bystanders take action. The Red Cross helps train you safely, effectively and confidently so you’re prepared for the moments that matter.

Why is CPR Important?

CPR should be used when you see someone who is unresponsive and is not breathing or only gasping. Having more bystanders trained in this simple skill can help save lives by putting more cardiac arrest victims within a few steps of lifesaving assistance.

What Are the Types of CPR?

* Hands-Only CPR: Hands-only CPR is an easy-to-learn skill that could save a life. It involves calling 9-1-1, sending someone for the AED if available and then giving continuous chest compressions. It only takes minutes to learn.

* Full CPR With Rescue Breaths: While Hands-only CPR can be lifesaving, learning full CPR is still very important. Getting trained in full CPR – combinations of chest compressions and rescue breaths – will increase your confidence and may enable you to help in other types of emergencies. Full CPR is ideal for all ages, and especially for people who are more likely to experience respiratory emergencies such as children and infants.

Why Learn CPR?

Learning how to perform CPR properly takes just a few short hours, but it can change a life forever. Red Cross CPR training classes give you the information and the skills you need to help adults, children and infants during cardiac emergencies. Whether you choose 100% in-person or blended learning CPR classes, our world-class instructors deliver the most up-to-date information that's engaging and effective, preparing you for the moments that matter.

Benefits to Being CPR Certified

* An Emergency Can Happen When You Least Expect It. No one ever expects emergencies to occur as they go about their day, which is why it is important to learn CPR ahead of time. Cardiac arrest can happen at home, at school, at the gym, on an airplane, in the workplace or anywhere in the community. CPR is a critical skill that can help save a life when a person's breathing or heart stops.
* Every Second Counts. You may be wondering, "why learn CPR when I can just call 9-1-1?" While you should always call 9-1-1 first in the event of an emergency, it still takes rescuers some time to arrive at the scene. For every minute without intervention, the chance of survival drops for a person experiencing sudden cardiac arrest. CPR can significantly improve someone’s chance of surviving when bystanders take prompt action.
* CPR Also Prevents Brain Death. Even if someone survives cardiac arrest, they may suffer permanent brain damage when they don't receive enough blood flow and oxygen to the brain. CPR certification can help prevent brain damage and death by keeping oxygenated blood moving throughout the body.
* Anyone Can Learn It. Another benefit of CPR is that this lifesaving training is for everyone. It only takes a few hours, and it can give you the skills and confidence to act in an emergency and help save a life. You'll find classes that are designed for the way you live and learn, with options available on weekdays and weekends in a variety of formats.
* You'll Have the Confidence to Act when Needed. CPR instruction will give you the skills and confidence to perform this life-saving procedure when it's needed the most. Plus, to keep your skills fresh, online refresher materials are available that can help you retain the knowledge you've gained. In addition, you'll also have access to a printable list of the basic steps for performing CPR. This way, you can keep the information you need right at your fingertips.

Cardiac Arrest Chain of Survival

Cardiac arrest can happen anytime and anywhere. In these emergencies, the heart stops beating or beats too ineffectively to circulate blood to the brain and other vital organs. The cardiac arrest out-of-hospital chain of survival shows the steps necessary to take in order to improve chances of survival from cardiac arrest.

The 6 links in the adult out-of-hospital Chain of Survival are:

* Recognition of cardiac arrest and activation of the emergency response system (such as calling 9-1-1)
* Early CPR with an emphasis on chest compressions
* Rapid defibrillation
* Advanced resuscitation by Emergency Medical Services (EMS) and other healthcare providers
* Post-cardiac arrest care in the hospital
* Recovery (such as additional treatment, rehabilitation, and psychological support)

CPR/AED Classes

At the Red Cross, you can choose the type of class for your schedule – and the way you learn best. For those who want to become certified in CPR/AED, you can choose from three types of courses:

* In-person: Designed for those who learn best in a traditional classroom setting, our in-person courses combine lecture with hands-on skills sessions. This way, you can not only learn what CPR is, but you will be able to practice your skills with a certified instructor. If the course is completed with a passing grade, you'll receive a two-year certification.

* Online: Perfect for those who want the freedom to take self-paced courses, our online classes can help you learn what CPR is and how to perform the different types of CPR. However, online safety training courses do not allow you to demonstrate your skill proficiency to a certified instructor, and therefore your certification may not meet the requirements for workplace safety.

* Blended Learning: Our blended learning programs combine self-paced, interactive instruction and in-person skills sessions. That way, you can learn what CPR is, why CPR is important and how to perform it in theory and in practice. Additionally, because this option allows you to demonstrate your skills to a certified instructor, you can receive full certification with a passing score.

cpr-class-with-instructors-talking-demonstrating-firt-aid-compressions-ans-reanimation-procedure-cpr-dummy-1-1536x1024.jpg

Jai Ganesh · Science HQ

Duodenum

Gist

The duodenum is the first, shortest (approx. 25–30 cm), and most fixed "C"-shaped section of the small intestine, connecting the stomach to the jejunum. It neutralizes acidic chyme and breaks down fats, proteins, and carbohydrates using bile and pancreatic enzymes, playing a critical role in nutrient absorption.

What is the main function of the duodenum?

The first part of the small intestine. It connects to the stomach. The duodenum helps to further digest food coming from the stomach. It absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body.

Summary

The duodenum is the first section of the small intestine in most vertebrates, including mammals, reptiles, and birds. In mammals, it may be the principal site for iron absorption. The duodenum precedes the jejunum and ileum and is the shortest part of the small intestine.

In humans, the duodenum is a hollow jointed tube about 25–38 centimetres (10–15 inches) long connecting the stomach to the jejunum, the middle part of the small intestine. It begins with the duodenal bulb, and ends at the duodenojejunal flexure marked by the suspensory muscle of duodenum. The duodenum can be divided into four parts: the first (superior), the second (descending), the third (transverse) and the fourth (ascending) parts.

Overview

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine may be used instead of duodenum. In mammals the duodenum may be the principal site for iron absorption.

In humans, the duodenum is a C-shaped hollow jointed tube, 25–38 centimetres (10–15 inches) in length, lying adjacent to the stomach (and connecting it to the small intestine). It is divided anatomically into four sections. The first part lies within the peritoneum but its other parts are retroperitoneal.

Details

The duodenum is the first part of your small intestine. Its main job is to transform the partially digested food it receives from your stomach into nutrients your body can use. Digestive juices from your liver, gallbladder and pancreas empty into your duodenum, helping with digestion and absorption.

Overview:

What is the duodenum?

The duodenum is the first part of your small intestine. Despite what the name suggests, your “small” intestine is the longest part of your digestive tract and plays a big role in your digestive system. Inside its many coils, digestive juices transform food into the nutrients (like proteins, fats, vitamins and water) that power your body.

The duodenum is a short, “C”-shaped chute. It’s the first stop food makes as it travels from your stomach to your small intestine. The other parts of your small intestine are your jejunum (the middle part) and ileum (the last part).

Function:

What is the function of the duodenum?

The duodenum continues the process of digestion (breakdown of food into nutrients) that starts in other parts of your gastrointestinal (GI) tract, like your mouth and stomach. It also begins the absorption process (moving the nutrients into your bloodstream). Think of it this way: Before reaching your duodenum, saliva and stomach acid have transformed food into food slush. Inside your duodenum, the slush becomes nutrients your body can use.

Your duodenum:

* Makes food traveling from your stomach less acidic. The partially digested food that travels from your stomach to your duodenum is called chyme. Chyme is highly acidic, thanks to stomach juices that break down food. Your duodenum releases a hormone (secretin) that triggers the release of an enzyme called bicarbonate that makes chyme less acidic. The breakdown of acid helps your digestive system absorb nutrients. It prevents the acid from damaging your small intestine.
* Transforms chyme into nutrients. Your duodenum releases a hormone (cholecystokinin) that triggers your pancreas, gallbladder and liver to release substances that help turn chyme into nutrients. Your liver and gallbladder release bile, which breaks down fats. Your pancreas releases lipase, which also breaks down fats, amylase to break down carbohydrates and protease to break down proteins. Your bloodstream absorbs these nutrients.
* Moves food molecules along. The duodenum pushes food molecules that don’t get absorbed into the next section of your small intestine, the jejunum. The duodenum squeezes and relaxes, creating a wave-like forward motion called peristalsis.

Anatomy:

How big is the duodenum?

It’s the shortest section of your small intestine, approximately 10 inches long — just 2 inches shy of a foot. “Duodenum,” translated from Latin, means “12 fingers,” a reference to its size. The length of your duodenum is approximately the width of 12 fingers placed side by side.

To put this in perspective, your entire small intestine is 22 feet long. If you stretched it out, it would be the length of a tennis court. Your duodenum wouldn’t be a single foot of the total length. Yet, important nutrient absorption happens in these 10 inches of your small intestine.

Where is the duodenum located?

Your duodenum starts just below your stomach. It curves to the right and back, down and then to the left in a “C” or horseshoe shape. It slants upward slightly before joining with the next part of your small intestine, your jejunum. The head of your pancreas (the widest part) sits inside the “C.”

What are the parts of the duodenum?

There are four basic parts. They get their name from their location and shape.

* Superior segment

The superior segment is the top part of the duodenum that connects with your stomach. It’s about 2 inches long. The part of the superior segment that connects directly with your pylorus (the stomach valve that opens to allow food to travel to your small intestine) is called the duodenal bulb. Most ulcers in your small intestine form here, where stomach acid is most likely to come into contact with your duodenum.

* Descending segment

As the name suggests, the descending segment is the part of the “C” shape that goes downward. It passes in front of your right kidney and is about 4 inches long.

This part of your small intestine connects to your pancreas (via the pancreatic duct) and your gallbladder and liver (via the common bile duct). “Ducts” are like tiny canals that allow substances to travel from one organ (like your liver) to another organ (like your small intestine). These organs produce substances that empty into the descending segment, breaking down fats, proteins and carbohydrates.

* Horizontal (inferior) segment

The horizontal segment is about 4 inches long. It extends from right to left and passes over essential blood vessels, including your aorta and inferior vena cava.

* Ascending segment

This is the smallest part of your duodenum, at just under an inch. It extends slightly upward and is located to the left of your aorta. It connects to your jejunum.

What is the duodenum made of?

The duodenum has four layers. Its cell makeup is the same as other organs in your GI tract. From the innermost layer to the outermost layer, the duodenum consists of the:

* Mucosa: It contains glands and fingerlike projections called microvilli. The microvilli increase the surface area of your duodenum, allowing it to absorb more nutrients than if it were flat.
* Submucosa: This layer consists of blood vessels and connective tissue. The submucosa contains Brunner’s glands. Brunner’s glands release a substance that makes chyme less acidic.
* Muscularis: This layer is mostly smooth muscle. Its job is mixing and moving. As it contracts, it blends the enzymes and bile that break down chyme. It also moves the chyme along the length of your duodenum, so it reaches your jejunum.
* Serosa: This layer consists of squamous epithelial cells that serve as your duodenum’s protective barrier.

Conditions and Disorders:

What problems can occur in the duodenum?

As the part of your small intestine closest to your stomach, your duodenum is especially susceptible to injury if you have excess stomach acid. The acid can lead to open stores in your stomach (peptic ulcers) and in your duodenum. The most common causes of these ulcers are H. pylori infection and overusing medicines called NSAIDs (nonsteroidal anti-inflammatory drugs). NSAIDs, like aspirin and ibuprofen, can ease symptoms like aches and pains but can cause ulcers if you use them too much.

If an untreated ulcer breaks down too much of your duodenum’s protective barrier, its contents can leak out and damage the gastroduodenal artery behind it. This can cause severe bleeding that requires emergency care.

Many of the same conditions that affect your small intestine, in general, can affect your duodenum specifically. Conditions that can affect your duodenum include:

* Brunner’s gland adenomas: Benign (noncancerous) growths that start in Brunner’s glands.
* Crohn’s disease: A type of irritable bowel disease (IBD) that causes irritation and inflammation.
* Celiac disease: A disorder that causes problems in your digestive system when you eat gluten.
* Duodenal atresia: A condition that causes a baby to be born with a closed duodenum.
* Duodenal stenosis: A condition that causes a baby to be born with a narrowed (but not completely closed) duodenum.
* Duodenal cancer: Cancer that starts in your duodenum.
* Duodenal diverticulum: A small, pouch-like structure that pushes outside the wall of your duodenum. Diverticula (plural of diverticulum) usually don’t cause issues or require treatment unless they become infected and inflamed (diverticulitis).
* Duodenitis: Inflammation in your duodenum.
* Small bowel obstruction: A medical emergency that happens when part of your small intestine (including your duodenum) is entirely or partially blocked.

Common signs or symptoms of issues with the duodenum

Symptoms depend on the specific condition. In general, symptoms of a condition affecting your duodenum are similar to problems with your GI tract. Signs and symptoms include:

* Abdominal pain.
* Bloating and gas.
* Constipation.
* Diarrhea.
* Nausea and vomiting.
* Indigestion (stomach discomfort after you eat).
* Bloody vomit or poop (a sign of a bleeding ulcer).

Common tests to check the health of the duodenum.

Common tests include:

* Breath test to check for H. pylori infections.
* Imaging procedures — like ultrasounds, X-rays, CT scans (computed tomography scans) and MRIs (magnetic resonance imaging) — that look for growths and inflammation inside your duodenum.
* Procedures that use a scope to see inside your duodenum, including enteroscopy and upper endoscopy.
* Biopsies to check abnormal growths, including cancer.

What are common treatments for conditions affecting the duodenum?

Common treatments include:

* Antibiotics to treat infections (like H. pylori).
* Corticosteroids to reduce severe inflammation.
* Medicines to reduce the amount or acidity level of stomach acid, like proton pump inhibitors (PPIs), histamine receptor blockers (H2 blockers) and antacids.
* Surgery to correct structural issues or treat cancer, including the Whipple procedure.

Care:

How can I keep my duodenum healthy?

Putting healthy habits into place to prevent irritating or overworking your digestive system is good for your entire GI tract, including your duodenum.

Choose a diet that keeps your digestive system running smoothly. Eating lots of fiber and drinking lots of water can help you have regular bowel movements so things don’t get backed up in your small intestine. Eating lots of vegetables and nonacidic foods can help you maintain a healthy acidity level in your gut.

Avoid substances that can irritate your gut. Smoking and drinking too much alcohol can irritate organs in your digestive system, including your small intestine. Taking too many NSAIDs (Nonsteroidal anti-inflammatory drugs) can lead to painful ulcers that require treatment.

Don’t ignore signs of digestive system issues. Changes in your bowel habits and unpleasant symptoms, like an upset stomach or indigestion, can be temporary. Or they can sound the alarm bells that you need to change your lifestyle or see a provider. Don’t delay getting help if you’ve got unpleasant digestive symptoms that aren’t improving.

Additional Information

Duodenum is the first part of the small intestine, which receives partially digested food from the stomach and begins the absorption of nutrients. The duodenum is the shortest segment of the intestine and is about 23 to 28 cm (9 to 11 inches) long. It is roughly horseshoe-shaped, with the open end up and to the left, and it lies behind the liver. On anatomic and functional grounds, the duodenum can be divided into four segments: the superior (duodenal bulb), descending, horizontal, and ascending duodenum.

A liquid mixture of food and gastric secretions enters the superior duodenum from the pylorus of the stomach, triggering the release of pancreas-stimulating hormones (e.g., secretin) from glands (crypts of Lieberkühn) in the duodenal wall. So-called Brunner glands in the superior segment provide additional secretions that help to lubricate and protect the mucosal layer of the small intestine. Ducts from the pancreas and gallbladder enter at the major duodenal papilla (papilla of Vater) in the descending duodenum, bringing bicarbonate to neutralize the acid in the gastric secretions, pancreatic enzymes to further digestion, and bile salts to emulsify fat. A separate minor duodenal papilla, also in the descending segment, may receive pancreatic secretions in small amounts. The mucous lining of the last two segments of the duodenum begins the absorption of nutrients, in particular iron and calcium, before the food contents enter the next part of the small intestine, the jejunum.

Inflammation of the duodenum is known as duodenitis, which has various causes, prominent among them infection by the bacterium Helicobacter pylori. H. pylori increases the susceptibility of the duodenal mucosa to damage from unneutralized digestive acids and is a major cause of peptic ulcers, the most common health problem affecting the duodenum. Other conditions that may be associated with duodenitis include celiac disease, Crohn disease, and Whipple disease. The horizontal duodenum, because of its location between the liver, pancreas, and major blood vessels, can become compressed by those structures in people who are severely thin, requiring surgical release to eliminate painful duodenal dilatation, nausea, and vomiting.

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2530) Amphibian

Gist

Amphibians are cold-blooded, vertebrate animals (possessing a backbone) that inhabit both aquatic and terrestrial environments. The name derives from Greek, meaning "living a double life" because they typically undergo metamorphosis, starting life in water with gills and developing lungs for land-based adult life.

The word amphibian was taken from the Greek “amphi” meaning “double” and “bios” meaning “life” which is quite fitting as these creatures do live a double life. Emerging from eggs that are usually laid in the water, most amphibians begin their life with gills.

Summary

Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all tetrapods, but excluding the amniotes (tetrapods with an amniotic membrane, such as modern reptiles, birds and mammals). All extant (living) amphibians belong to the monophyletic subclass Lissamphibia, with three living orders: Anura (frogs and toads), Urodela (salamanders), and Gymnophiona (caecilians). Evolved to be mostly semiaquatic, amphibians have adapted to inhabit a wide variety of habitats, with most species living in freshwater, wetland or terrestrial ecosystems (such as riparian woodland, fossorial and even arboreal habitats). Their life cycle typically starts out as aquatic larvae with gills known as tadpoles, but some species have developed behavioural adaptations to bypass this.

Young amphibians generally undergo metamorphosis from an aquatic larval form with gills to an air-breathing adult form with lungs. Amphibians use their skin as a secondary respiratory interface, and some small terrestrial salamanders and frogs even lack lungs and rely entirely on their skin. They are superficially similar to reptiles like lizards, but unlike reptiles and other amniotes, require access to water bodies to breed. With their complex reproductive needs and permeable skins, amphibians are often ecological indicators to habitat conditions; in recent decades there has been a dramatic decline in amphibian populations for many species around the globe.

The earliest amphibians evolved in the Devonian period from tetrapodomorph sarcopterygians (lobe-finned fish with articulated limb-like fins) that evolved primitive lungs, which were helpful in adapting to dry land. They diversified and became ecologically dominant during the Carboniferous and Permian periods, but were later displaced in terrestrial environments by early reptiles and basal synapsids (predecessors of mammals). The origin of modern lissamphibians, which first appeared during the Early Triassic, around 250 million years ago, has long been contentious. The most popular hypothesis is that they likely originated from temnospondyls, the most diverse group of prehistoric amphibians, during the Permian period. Another hypothesis is that they emerged from lepospondyls. A fourth group of lissamphibians, the Albanerpetontidae, became extinct around 2 million years ago.

The number of known amphibian species is approximately 8,000, of which nearly 90% are frogs. The smallest amphibian (and vertebrate) in the world is a frog from New Guinea (Paedophryne amauensis) with a length of just 7.7 mm (0.30 in). The largest living amphibian is the 1.8 m (5 ft 11 in) South China giant salamander (Andrias sligoi), but this is dwarfed by prehistoric temnospondyls such as Mastodonsaurus which could reach up to 6 m (20 ft) in length. The study of amphibians is called batrachology, while the study of both reptiles and amphibians is called herpetology.

Details

An amphibian is (class Amphibia), any member of the group of vertebrate animals characterized by their ability to exploit both aquatic and terrestrial habitats. The name amphibian, derived from the Greek amphibios meaning “living a double life,” reflects this dual life strategy—though some species are permanent land dwellers, while other species have a completely aquatic mode of existence.

Approximately 8,100 species of living amphibians are known. First appearing about 340 million years ago during the Middle Mississippian Epoch, they were one of the earliest groups to diverge from ancestral fish-tetrapod stock during the evolution of animals from strictly aquatic forms to terrestrial types. Today amphibians are represented by frogs and toads (order Anura), newts and salamanders (order Caudata), and caecilians (order Gymnophiona). These three orders of living amphibians are thought to derive from a single radiation of ancient amphibians, and although strikingly different in body form, they are probably the closest relatives to one another. As a group, the three orders make up subclass Lissamphibia. Neither the lissamphibians nor any of the extinct groups of amphibians were the ancestors of the group of tetrapods that gave rise to reptiles. Though some aspects of the biology and anatomy of the various amphibian groups might demonstrate features possessed by reptilian ancestors, amphibians are not the intermediate step in the evolution of reptiles from fishes.

Modern amphibians are united by several unique traits. They typically have a moist skin and rely heavily on cutaneous (skin-surface) respiration. They possess a double-channeled hearing system, green rods in their retinas to discriminate hues, and pedicellate (two-part) teeth. Some of these traits may have also existed in extinct groups.

Members of the three extant orders differ markedly in their structural appearance. Frogs and toads are tailless and somewhat squat with long, powerful hind limbs modified for leaping. In contrast, caecilians are limbless, wormlike, and highly adapted for a burrowing existence. Salamanders and newts have tails and two pairs of limbs of roughly the same size; however, they are somewhat less specialized in body form than the other two orders.

Many amphibians are obligate breeders in standing water. Eggs are laid in water, and the developing larvae are essentially free-living embryos; they must find their own food, escape predators, and perform other life functions while they continue to develop. As the larvae complete their embryonic development, they adopt an adult body plan that allows them to leave aquatic habitats for terrestrial ones. Even though this metamorphosis from aquatic to terrestrial life occurs in members of all three amphibian groups, there are many variants, and some taxa bear their young alive. Indeed, the roughly 8,100 living species of amphibians display more evolutionary experiments in reproductive mode than any other vertebrate group. Some taxa have aquatic eggs and larvae, whereas others embed their eggs in the skin on the back of the female; these eggs hatch as tadpoles or miniature frogs. In other groups, the young develop within the oviduct, with the embryos feeding on the wall of the oviduct. In some species, eggs develop within the female’s stomach.

The three living orders of amphibians vary greatly in size and structure. The presence of a long tail and two pairs of limbs of about equal size distinguishes newts and salamanders (order Caudata) from other amphibians, although members of the eel-like family Sirenidae have no hind limbs. Newts and salamanders vary greatly in length; members of the Mexican genus Thorius measure 25 to 30 mm (1 to 1.2 inches), whereas Andrias, a genus of giant aquatic salamanders endemic to China and Japan, reaches a length of more than 1.5 metres (5 feet). Frogs and toads (order Anura) are easily identified by their long hind limbs and the absence of a tail. They have only five to nine presacral vertebrae. The West African goliath frog, which can reach 30 cm (12 inches) from snout to vent and weigh up to 3.3 kg (7.3 pounds), is the largest anuran. Some of the smallest anurans include the South American brachycephalids, which have an adult snout-to-vent length of only 9.8 mm (0.4 inch), and some microhylids, which grow to 9 to 12 mm (0.4 to 0.5 inch) as adults. The long, slender, limbless caecilians (order Gymnophiona) are animals that have adapted to fossorial (burrowing) lifestyles by evolving a body segmented by annular grooves and a short, blunt tail. Caecilians can grow to more than 1 metre (3 feet) long. The largest species, Caecilia thompsoni, reaches a length of 1.5 metres (5 feet), whereas the smallest species, Idiocranium russeli, is only 90 to 114 mm (3.5 to 5 inches) long.

Distribution and abundance

Amphibians occur widely throughout the world, even edging north of the Arctic circle in Eurasia; they are absent only in Antarctica, most remote oceanic islands, and extremely xeric (dry) deserts. Frogs and toads show the greatest diversity in humid tropical environments. Salamanders primarily inhabit the Northern Hemisphere and are most abundant in cool, moist, montane forests; however, members of the family Plethodontidae, the lungless salamanders, are diverse in the humid tropical montane forests of Mexico, Central America, and northwestern South America. Caecilians are found spottily throughout the African, American, and Asian wet tropics.

For many years, habitat destruction has had a severe impact on the distribution and abundance of numerous amphibian species. Since the 1980s, a severe decline in the populations of many frog species has been observed. Although acid rain, global warming, and ozone depletion are contributing factors to these reductions, a full explanation of the disappearance in diverse environment remains uncertain. A parasitic fungus, the so-called amphibian chytrid (Batrachochytrium dendrobatidis), however, appears to be a major cause of substantial frog die-offs in parts of Australia and southern Central America and milder events in North America and Europe.

Economic importance

Amphibians, especially anurans, are economically useful in reducing the number of insects that destroy crops or transmit diseases. Frogs are exploited as food, both for local consumption and commercially for export, with thousands of tons of frog legs harvested annually. The skin secretions of various tropical anurans are known to have hallucinogenic effects and effects on the central nervous and respiratory systems in humans. Some secretions have been found to contain magainin, a substance that provides a natural antibiotic effect. Other skin secretions, especially toxins, have potential use as anesthetics and painkillers. Biochemists are currently investigating these substances for medicinal use.

Natural history:

Reproduction

The three living groups of amphibians have distinct evolutionary lineages and exhibit a diverse range of life histories. The breeding behaviour of each group is outlined below. One similar tendency among amphibians has been the evolution of direct development, in which the aquatic egg and free-swimming larval stages are eliminated. Development occurs fully within the egg capsule, and juveniles hatch as miniatures of the adult body form. Most species of lungless salamanders (family Plethodontidae), the largest salamander family, some caecilians, and many species of anurans have direct development. In addition, numerous caecilians and a few species of anurans and salamanders give birth to live young (viviparity).

Anurans display a wide variety of life histories. Centrolenids and phyllomedusine hylids deposit eggs on vegetation above streams or ponds; upon hatching, the tadpoles (anuran larvae) drop into the water where they continue to develop throughout their larval stage. Some species from the families Leptodactylidae and Rhacophoridae create foam nests for their eggs in aquatic, terrestrial, or arboreal habitats; after hatching, tadpoles of these families usually develop in water. Dendrobatids and other anurans deposit their eggs on land and transport them to water. Female hylid marsupial frogs are so called because they carry their eggs in a pouch on their backs. A few species lack a pouch and the tadpoles are exposed on the back; in some species, the female deposits her tadpoles in a pond as soon as they emerge.

Embryonic stage

Inside the egg, the embryo is enclosed in a series of semipermeable gelatinous capsules and suspended in perivitelline fluid, a fluid that also surrounds the yolk. The hatching larvae dissolve these capsules with enzymes secreted from glands on the tips of their snouts. The original yolk mass of the egg provides all nutrients necessary for development; however, various developmental stages utilize different nutrients. In early development, fats are the major energy source. During gastrulation, an early developmental stage in which the embryo consists of two cell layers, there is an increasing reliance on carbohydrates. After gastrulation, a return to fat utilization occurs. During the later developmental stages, when morphological structures form, proteins are the primary energy source. By the neurula stage, an embryonic stage in which nervous tissue develops, cilia appear on the embryo, and the graceful movement of these hairlike structures rotates the embryo within the perivitelline fluid. The larvae of direct developing and live-bearing caecilians, salamanders, and some anurans have external gills that press against the inner wall of the egg capsule, which permits an exchange of gases (oxygen and carbon dioxide) with the outside air or with maternal tissues. During development, ammonia is the principal form of nitrogenous waste, and it is diluted by a constant diffusion of water in the perivitelline fluid.

The development of limbs in the embryos of aquatic salamanders begins in the head region and proceeds in a wave down the body, and digits appear sequentially on both sets of limbs. Salamanders that deposit their eggs in streams produce embryos that develop both sets of limbs before they hatch, but salamanders that deposit their eggs in still water have embryos that develop only forelimbs before hatching. (In contrast, the limbs of anurans do not appear until after hatching.) Soon after the appearance of forelimbs, most pond-dwelling salamanders develop an ectodermal projection known as a balancer on each side of the head. These rodlike structures arise from the mandibular arch, contain nerves and capillaries, and produce a sticky secretion. They keep newly hatched larvae from sinking into the sediment and aid the salamander in maintaining its balance before its forelimbs develop. After the forelimbs appear, the balancers degenerate.

During the embryonic and early larval stages in anurans, paired adhesive organs arise from the hyoid arch, located at the base of the tongue. The sticky mucus they secrete can form a threadlike attachment between a newly hatched tadpole and the egg capsule or vegetation. Consequently, the tadpole that is still developing can remain in a stable position until it is capable of swimming and feeding on its own, after which the adhesive organs degenerate.

Larval stage

The amphibian larva represents a morphologically distinct stage between the embryo and adult. The larva is a free-living embryo. It must find food, avoid predators, and participate in all other aspects of free-living existence while it completes its embryonic development and growth. Salamander and caecilian larvae are carnivorous, and they have a morphology more like their respective adult forms than do anuran larvae. Not long after emerging from their egg capsules, larval salamanders, which have four fully developed limbs, start to feed on small aquatic invertebrates. The salamander larvae are smaller versions of adults, although they differ from their adult counterparts by the presence of external gills, a tailfin, distinctive larval dentition, a rudimentary tongue, and the absence of eyelids. Larval caecilians, also smaller models of adults, have external gills, a lateral-line system (a group of epidermal sense organs located over the head and along the side of the body), and a thin skin.

In anurans, tadpoles are fishlike when they hatch. They have short, generally ovoid bodies and long, laterally compressed tails that are composed of a central axis of musculature with dorsal and ventral fins. The mouth is located terminally (recessed), ringed with an oral disk that is often fringed by papillae and bears many rows of denticles made of keratin. Tadpoles often have horny beaks. Their gills are internal and covered by an operculum. Water taken in through the mouth passes over the gills and is expelled through one or more spiracular openings on the side of an opercular chamber. Anuran larvae are microphagous and thus feed largely on bacteria and algae that coat aquatic plants and debris.

Salamander larvae usually reach full size within two to four months, although they may remain larvae for two to three years before metamorphosis occurs. Some large aquatic species, such as the hellbender (Cryptobranchus alleganiensis) and the mud puppy (Necturus maculosus), never fully metamorphose and retain larval characteristics as adults (see below heterochrony). Tadpole development varies in length between species. Some anuran species living in xeric (dry) habitats, in which ephemeral ponds may exist for only a few weeks, develop and metamorphose within two to three weeks; however, most species require at least two months. Species living in cold mountain streams or lakes often require much more time. For example, the development of the tailed frog (Ascaphus truei) takes three years to complete.

Metamorphosis

Metamorphosis entails an abrupt and thorough change in an animal’s physiology and biochemistry, with concomitant structural and behavioral modifications. These changes mark the transformation from embryo to juvenile and the completion of development. Hormones ultimately control all events of larval growth and metamorphosis, and in many instances, development is accompanied by a shift from a fully aquatic life to a semiaquatic or fully terrestrial one.

Although salamanders undergo many structural modifications, these changes are not dramatic. The skin thickens as dermal glands develop and the caudal fin is resorbed. Gills are resorbed and gill slits close as lungs develop and branchial (gill) circulation is modified. Eyelids, tongue, and a maxillary bone are formed, and teeth develop on the maxillary and parasphenoid bones. Changes that occur in caecilians—the closure of the gill slit, the degeneration of the caudal fin, and the development of a tentacle and skin glands—are also minor.

Skeletal changes are much more dramatic in anurans because tadpoles make an abrupt and radical transition to their adult form. Limbs complete their development, and the forelimbs break through the opercular wall, early in metamorphosis. The tail shrinks as it is resorbed by the body, dermal glands develop, and the skin becomes thicker. As lungs and pulmonary ventilation develop, gills and their associated blood circulation disappear. Adult mouthparts replace their degenerating larval equivalents, and hyolaryngeal structures develop. All anurans except pipids (family Pipidae) develop a tongue. In the newly differentiated digestive tract, the intestine is shortened. The eyes become larger and are structurally altered; eyelids appear. These extreme changes of anuran metamorphosis clearly demarcate the shift from an aquatic to a terrestrial mode of life. Other less obvious yet nonetheless radical modifications of the larval skull and hyobranchial apparatus (that is, the part of the skeleton that serves as base for the tongue on the floor of the mouth) occur to make room for newly developed sense organs. These modifications also facilitate the transition from larval modes of feeding and respiration to those of the adult.

During metamorphosis, the urogenital system of all amphibians is also modified. A mesonephric or opisthonephric kidney—which uses nephrons located either in the middle or at the end of the nephric ridge in the developing embryo—replaces the degenerating rudimentary pronephric kidney. This transition is linked to the shift from production of a large volume of dilute ammonia to a small amount of concentrated urea. Gonads and associated ducts also appear and begin their maturation.

Heterochrony

Neoteny, once a widely used label for the condition of sexually mature larvae, has been discontinued by biologists and replaced by the concept of heterochrony. Heterochrony refers to the change in the timing and rate of developmental events, and it is a widespread feature in amphibian evolution, particularly in salamanders. During development, a structure can begin to develop sooner (predisplacement) or later (postdisplacement) in an organism than it occurred in the ancestral species or parents. Also, a structure may continue to develop beyond the previous embryological sequence (hypermorphosis) or the developmental sequence can stop earlier than normal (progenesis or hypomorphosis). Each of these heterochronic events can produce a structurally or functionally different organism.

The classical “neotenic” salamander, the axolotl (Ambystoma mexicanum), is a paedomorphic species (that is, a species that retains aspects of its juvenile form during its adult phase); it retains its larval gills. In the mole salamander (Ambystoma talpoideum), some populations also display hypomorphic development in which the development of several larval traits to the adult condition is delayed. Since the gonads mature, a population of sexually mature salamanders with a larval morphology is produced. Heterochrony also explains the presence of larval traits in adults of the salamander families Cryptobranchidae (hellbenders) and Proteidae (olms and mud puppies).

Heterochrony is not confined to salamanders. The different sized eardrums in the American bullfrog (Lithobates catesbeianus) are examples of hypermorphism in male bullfrogs. The development of the eardrums in the male extends beyond that of the female.

Life cycle

Many amphibians have a biphasic life cycle involving aquatic eggs and larvae that metamorphose into terrestrial or semiaquatic juveniles and adults. Commonly, they deposit large numbers of eggs in water; clutches of the tiger salamander (Ambystoma tigrinum) may exceed 5,000 eggs, and large bullfrogs (L. catesbeianus) may produce clutches of 45,000 eggs. Egg size and water temperature are important factors that influence an embryo’s development time. Eggs of many anuran species laid in warm water require only one or two days to develop, whereas eggs deposited in cold mountain lakes or streams may not hatch for 30 to 40 days. The development of salamander eggs often requires more time, with hatching occurring 20 to 270 days after fertilization.

Food and feeding

Adult amphibians consume a wide variety of foods. Earthworms are the main diet of burrowing caecilians, whereas anurans and salamanders feed primarily on insects and other arthropods. Large salamanders and some large anurans eat small vertebrates, including birds and mammals. Most anurans and salamanders locate prey by sight, although some use their sense of smell. The majority of salamanders and diurnal (that is, active during daylight) terrestrial anurans are active foragers, but many other anurans employ a sit-and-wait technique. Caecilians locate their underground prey with a chemosensory tentacle and capture their quarry with a powerful bite (see chemoreception). Aquatic salamanders lunge at their prey with an open mouth and appear to drag the victim in by expanding their buccal (oral) cavity. The terrestrial lunged salamander extends its sticky tongue, which is attached anteriorly to the floor of the mouth, to ensnare a meal. In lungless salamanders, the hyobranchial apparatus is not part of the process of buccal respiration; this apparatus is modified so that it can project the tongue from the mouth. The end of the tongue is sticky to adhere to prey, and prey can be captured at distances ranging from 40 to 80 percent of the salamander’s body length.

Primitive anurans have feeding mechanisms that resemble those of the typical terrestrial salamanders. More advanced anurans employ a “lingual flip,” in which the surfaces of the retracted tongue are twisted and inverted in the fully extended tongue. The pipids, which are completely aquatic, are unique among anurans; they lack a tongue and thus must essentially drag food and water into their mouth.

Form and function:

Common features

Although the structure of the muscular, skeletal, and other anatomical systems are specifically modified for each group, amphibians are often set apart from other groups of animals by their characteristic skin, or integument, and evolutionary advances in vision and hearing.

The circulatory and respiratory systems work with the integument to provide cutaneous respiration. A broad network of cutaneous capillaries facilitates gas exchange and the diffusion of water and ions between the animal and the environment. Several species of salamanders and at least one species of frog (Barbourula kalimantanensis) are lungless. Amphibians also employ various combinations of branchial and pulmonary strategies to breathe. The buccal pump mechanism, which involves the pushing of air between the lungs and the closed mouth, is present in amphibians and some groups of fishes.

In addition to its roles in respiration and maintaining water balance, the integument of amphibians contains poison glands that release toxins. Specific toxins are found only in amphibians and are used to defend against predators.

The eye of the modern amphibian (or lissamphibian) has a lid, associated glands, and ducts. It also has muscles that allow its accommodation within or on top of the head, depth perception, and true colour vision. These adaptations are regarded as the first evolutionary improvements in vertebrate terrestrial vision. Green rods in the retina, which permit the perception of a wide range of wavelengths, are found only in lissamphibians.

The amphibian auditory system is also specially adapted. One modification is the papilla amphibiorum, a patch of sensory tissues that is sensitive to low-frequency sound. Also unique to lissamphibians is the columella-opercular complex, a pair of elements associated with the auditory capsule that transmit airborne (columella) or seismic (operculum) signals.

Structural differences

The environment helps to mold the morphology of an organism. The markedly different structural forms of the three living orders demonstrate that each group has had a long, separate evolutionary history.

Salamanders

Salamanders have less-specialized morphologies than do the other two orders. They have small heads and long slender bodies made up of four limbs and a tail. Although the skulls of most terrestrial salamanders consist of more individual pieces than do those of either caecilians or anurans, they are arched, narrow, and not well roofed. These skulls have an extra set of articulations with the vertebral column, a characteristic that may have been an evolutionary strategy for stabilizing the head on the axial skeleton (vertebral column) in terrestrial salamanders; other amphibians developed a specialized trunk musculature to meet this challenge.

The hyoid apparatus in the floor of the mouth enables salamanders to capture prey by projecting their fleshy tongues from the buccal cavity, although most are only able to roll their tongues forward over their lower jaws to snare their dinner. Food is held and manipulated in the buccal cavity by the teeth and tongue. This mechanism does not require adaptations to the mandibular and jaw muscles or sturdy, specialized teeth—features that most salamanders lack. Well-developed eyes and nasal organs, however, are needed to locate prey. Because salamanders do not depend on their vocal abilities, their auditory apparatus is less specialized than that of anurans.

Most salamander species have a generalized mode of locomotion, which is reflected by a lack of specialization in the musculoskeletal system. Salamanders walk methodically and move the limbs in the standard diagonal-sequence gait of quadrupeds. Aquatic salamanders show the greatest divergence from this generalized morphological pattern. Because they are kept afloat by their aquatic environment, they are often larger, devoid of limbs, and swim via the lateral undulation of the trunk and tail.

Caecilians

Of the three living amphibian orders, caecilians show the least divergence in structure and form. All caecilians, except for a few aquatic species, lead subterranean existences and thus have similar specialized morphologies. They have a wormlike appearance, with compact and bony heads in which the centres of ossification have fused to provide a strong, spadelike braincase. While useful in tunneling through the soil, this compact cranium does not allow much room for the jaw muscles to develop. Thus, the lower jaw is attached to the main adductor muscle of the jaw by a retroarticular process outside the cranium, and the caecilian cannot extend its tongue from the buccal cavity.

Vision, of little importance in the caecilian’s environment, is not acute; however, the nasal organs are well developed, and chemosensory perception is greatly enhanced by the existence of a tentacle (see chemoreception). The sense of hearing is probably less sensitive than that of salamanders or anurans. If the operculum (a feature analogous to auditory stapes) is present, it is incorporated into the columella (the rod made of bone or cartilage connecting the tympanic membrane with the internal ear).

Subterranean movement and feeding are aided by alterations of the axial musculoskeletal system. The overlying skin is attached to the axial muscles, and this creates a tough sheath that encases the long, muscular body and covers the posterior part of the skull. Caecilians move through soil by a process called concertina locomotion, in which the body alternately folds and extends itself along its entire length, often occurring within the envelope of skin as well as by flexures of the entire body.

Anurans

Anurans are more widespread, diverse, and numerous than either salamanders or caecilians. Anurans display a broader range of specialization in locomotion, feeding, and reproduction in their adaptation to many different environments and lifestyles. In general, anurans have a broad, flat head—which is almost as wide as their body—and a short trunk that, aside from the sacral area, is relatively inflexible. Long, powerful hind limbs propel the fused head and trunk in a forward trajectory. These leaping movements require more complex pectoral and pelvic girdles than that of salamanders. The pectoral girdle is designed to absorb the shock of the anuran as it lands on its forelimbs; an elastic, muscular suspension connecting the pectoral girdle to the skull and vertebral column provides this ability. The pelvic girdle horizontally flanks the coccyx, the bony rod at the posterior end of the vertebral column. Muscles and ligaments attach the pelvic girdle to the coccyx, sacrum, presacral vertebrae, and proximal part of the hind limb. Thus, when the animal jumps, the pelvic girdle lies in the same plane as the axial column, and, when the animal sits, the posterior end of the girdle is deflected ventrally.

In addition to the specializations for leaping, many anurans have developed structures that allow them to burrow or climb trees. These structures primarily involve modifications in limb proportions and iliosacral articulation. Arboreal (tree-dwelling) anurans have long limbs and digits with large, terminal, adhesive pads; anurans that burrow have short sturdy limbs and large spatulate tubercles made of keratin on their feet. The pipids, specialized for their aquatic environment, have little flexibility in their axial skeletons and instead propel their flat, fused bodies through the water with powerful hind limbs and large, fully webbed feet.

Anurans depend on their visual acumen for feeding and locomotion, and hence the eyes of most species are large and well developed. Because vocalizing is part of their mating and territorial behaviour, their ears are also well developed. Most species have an external tympanum (eardrum), a structure that is absent in salamanders and caecilians.

Additional Information

Amphibians are a class of cold-blooded vertebrates made up of frogs, toads, salamanders, newts, and caecilians (wormlike animals with poorly developed eyes). All amphibians spend part of their lives in water and part on land, which is how they earned their name—“amphibian” comes from a Greek word meaning “double life.” These animals are born with gills, and while some outgrow them as they transform into adults, others retain them for their entire lives.

Amphibians are the most threatened class of animals in nature. They are extremely susceptible to environmental threats because of their porous eggs and semipermeable skin. Every major threat, from climate change to pollution to disease, affects amphibians and has put them at serious risk.

Amphibians live part of their lives in water and part on land. They are vertebrates and are also ectothermic; they cannot regulate their own body heat, so they depend on sunlight to become warm and active. Amphibians also can't cool down on their own, so if they get too hot, they have to find a burrow or some other shade. In cold weather, amphibians tend to be sluggish and do not move around much.

Metamorphosis

Young amphibians do not look like their parents. Generally called larvae, they change in body shape, diet, and lifestyle as they develop, a process called metamorphosis. A frog is a good example, starting out as a tadpole with gills to breathe underwater and a tail to swim with. As the young frog gets older, it develops lungs, legs, and a different mouth. Its eyes also change position, and it loses its tail. At this point it is an adult frog and spends most of its time hopping on land rather than swimming like a fish in the water.

Moist is Best

Most amphibians have soft, moist skin that is protected by a slippery secretion of mucus. They also tend to live in moist places or near water to keep their bodies from drying out. Many adult amphibians also have poison-producing glands in their skin, which make them taste bad to predators and might even poison a predator that bites or swallows them. Some of these amphibians, like poison frogs, are brightly colored as a warning: Don't eat me, or you'll be sorry!

Three Groups

There are about 5,500 known amphibian species, divided into three main groups: salamanders and newts, caecilians, and frogs and toads. The largest amphibian is the Chinese giant salamander at nearly 6 feet (1.8 meters) and 140 pounds (63 kilograms), and the smallest is the gold frog at 0.39 inches (1 centimeter) long.

Amphibians-Names-List-in-English-with-their-Pictures.png

Jai Ganesh · This is Cool

Potassium Iodide

Gist

Potassium iodide (KI) is an inorganic compound used to protect the thyroid gland from radiation, treat iodine deficiency, and manage specific skin conditions. Primarily taken as a tablet, it blocks the absorption of radioactive iodine during emergencies and serves as a supplement to combat hyperthyroidism and goiter.

Potassium iodide (KI) is a medication used to protect the thyroid gland from radiation during emergencies, treat hyperthyroidism and thyroid storm, and act as an expectorant to loosen mucus in the lungs. It is also used to treat certain fungal infections (sporotrichosis) and chronic skin conditions like erythema nodosum.

Summary

Potassium iodide (KI) is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are used. It is also used for treating skin sporotrichosis and phycomycosis. It is a supplement used by people with low dietary intake of iodine. It is administered orally.

Common side effects include vomiting, diarrhea, abdominal pain, rash, and swelling of the salivary glands. Other side effects include allergic reactions, headache, goitre, and depression. While use during pregnancy may harm the baby, its use is still recommended in radiation emergencies. Potassium iodide has the chemical formula KI. Commercially it is made by mixing potassium hydroxide with iodine.

Potassium iodide has been used medically since at least 1820. It is on the World Health Organization's List of Essential Medicines. Potassium iodide is available as a generic medication and over the counter. Potassium iodide is also used for the iodization of salt.

Details

Potassium iodide (KI) is a medication that treats certain medical conditions — including some thyroid conditions — and protects your thyroid from radiation exposure. Never take KI without talking to a healthcare provider first. They’ll make sure it’s safe for you and explain proper dosing.

Overview:

What is potassium iodide?

Potassium iodide is a salt that healthcare providers sometimes use as a medication to treat certain thyroid conditions or protect your thyroid from radiation exposure.

Potassium iodide acts as a thyroid blocker, which means it stops your thyroid from releasing thyroid hormone. This can be useful in certain situations, like if your thyroid is producing high levels of thyroid hormone (hyperthyroidism). Potassium iodide can also help protect your thyroid from absorbing radioactive iodine that accidentally enters your body.

Healthcare providers intentionally use radioactive iodine — in controlled, safe amounts — for certain imaging tests and treatments. Nuclear weapon detonations and nuclear power plant accidents release unsafe amounts of radioactive iodine (radioiodine) into the air, water and soil. Potassium iodide can protect you from such unintended environmental exposure.

Potassium iodide comes in pill (tablet) and liquid forms. Some forms require a prescription, while others you can get over the counter (OTC). You should only take potassium iodide in any form if your healthcare provider or public health officials tell you to do so. Remember that just because you can buy something over the counter doesn’t mean it’s safe or appropriate for you to take.

What conditions are treated with potassium iodide?

Healthcare providers sometimes use potassium iodide to treat:

* Hyperthyroidism, particularly when associated with Graves’ disease.
* Thyroid storm.
* Some skin conditions, including cutaneous sporotrichosis (a fungal infection).
* Iodine deficiency.

Potassium iodide is also a prescription-strength expectorant. If you have a chronic lung disease, your healthcare provider may prescribe potassium iodide to loosen mucus and make it easier for you to cough.

Potassium iodide can also help protect your thyroid:

* During radiation emergencies (like a nuclear power plant meltdown).
* During medical testing (like MIBG scans) or treatments that expose your thyroid to radiation.

Potassium iodide for radiation

Potassium iodide is best known for protecting people during a radiation emergency. But it’s important to know there are limitations. Potassium iodide only protects your thyroid from radioactive iodine (one specific radioactive material). It doesn’t protect other parts of your body, and it doesn’t protect you from all the other radioactive materials you might be exposed to that could cause radiation sickness.

Healthcare providers and public health officials only recommend using potassium iodide in certain types of radiation emergencies. These typically include nuclear power plant accidents.

Potassium iodide won’t completely protect you if a nuclear bomb goes off because the greatest threat in that situation isn’t radioactive iodine. You’d be exposed to hundreds of other types of radioactive materials, and potassium iodide has no effect on those. If a bomb goes off, don’t worry about trying to find potassium iodide. Instead, seek shelter indoors and follow local officials’ guidance.

Thyroid protection after a nuclear power plant accident

Potassium iodide can help protect your thyroid from radioactive iodine released in a nuclear power plant accident. Here’s why. Your thyroid needs iodine to function normally and produce thyroid hormone. But it doesn’t know the difference between normal iodine (like what you get from your food) and radioactive iodine. This means your thyroid grabs iodine from wherever it can.

Nuclear power plant accidents may release radioactive iodine into the nearby environment. If you breathe in contaminated air or eat contaminated food, the radioactive iodine can enter your body. Your thyroid then absorbs it. Depending on the amount that gets into your body, radioactive iodine can damage your thyroid and potentially lead to thyroid cancer down the road.

The younger you are, the more vulnerable you are to the harmful effects of radioactive iodine. Babies and children face the greatest threat. If you’re pregnant, radioactive iodine is more dangerous for you compared to other adults because your thyroid is more active during pregnancy.

That’s where potassium iodide comes into play. It fills up your thyroid with enough iodine to keep it busy for a while. So, instead of absorbing the radioactive iodine, your thyroid ignores it, and the radioactive iodine passes out of your body in your pee.

Treatment Details:

How should I use potassium iodide?

Depending on your diagnosis, your healthcare provider may prescribe potassium iodide in tablet or liquid form. Your provider or local public health officials will tell you:

* How to take potassium iodide.
* When to take it.
* The appropriate dosage.

The dosage can vary widely according to the condition you’re treating. In the context of radiation emergencies, the recommended dosage varies according to a person’s age.

How long should I take potassium iodide?

It depends on the reason you’re taking it. Follow your healthcare provider’s guidance. In radiation emergencies, one dose typically protects you for about 24 hours. So, most people should take one dose per day until local officials say it’s safe to stop taking it.

Pregnant women and newborns should only take one dose (no repeat doses) unless told otherwise. That’s because potassium iodide may impact thyroid function in fetuses and newborns.

Risks / Benefits:

What are the potential benefits of potassium iodide?

When used during a radiation emergency, potassium iodide can lower a person’s risk of developing thyroid cancer down the road. This is especially important in children and adults under age 40, who face a greater risk of thyroid cancer from radioactive iodine exposure.

What are the side effects of potassium iodide?

Possible side effects of potassium iodide include:

* Skin rash.
* Swollen salivary glands.
* Metallic taste in your mouth.
* Burning of your mouth and throat.
* Sore teeth and gums.
* Upset stomach, nausea and diarrhea.
* Headache.
* Head cold symptoms, like a runny nose.

Newborns who are given more than a single dose of potassium iodide run the risk of developing hypothyroidism.

Can potassium iodide cause an allergic reaction?

Potassium iodide causes an allergic reaction in some people. Signs of an allergic reaction include:

* Fever.
* Joint pain.
* Swelling of your face, lips, tongue, throat, hands or feet.
* Wheezing and/or shortness of breath.
* Difficulty speaking or swallowing.

Call a healthcare provider right away if you develop signs of an allergic reaction. Call your local emergency number if you have trouble breathing, speaking or swallowing.

Taking more potassium iodide than healthcare providers or local officials recommend can make you very sick or even be fatal. That’s why it’s crucial to follow expert advice closely when taking potassium iodide or giving it to a child.

Is taking potassium iodide safe for me?

Potassium iodide isn’t safe for everyone. It’s important to check with your healthcare provider before taking potassium iodine to make sure it’s OK for you. In general, potassium iodine may not be safe to take if you:

* Have thyroid nodules as well as heart disease.
* Are taking certain medications, including those that affect how your thyroid works.
* Are sensitive or allergic to iodine.
* Have chronic kidney (renal) failure.
* Have tuberculosis or acute bronchitis.
* Have a history of adrenal insufficiency (Addison’s disease).
* Have a weakened immune system.
* Are pregnant or breastfeeding. In some situations, like radiation emergencies, the benefits of taking potassium iodide while pregnant or nursing may outweigh the risks. Follow your provider’s guidance closely.

Be sure to talk to your provider before starting potassium iodide or any other medicine. They’ll review your medical history and decide if it’s safe for you. They can tell you the benefits and risks of potassium iodide in your unique situation. They’ll also tell you if you need follow-ups or monitoring.

Recovery and Outlook:

Is there anything I can do to make this treatment easier on me?

Your provider may recommend taking potassium iodide along with milk or juice to limit stomach upset. Talk to your provider if you’re concerned about side effects or have a history of any medication allergies.

Additional Information

* In a radiation emergency, some people may be told to take potassium iodide (KI) to protect their thyroid.
* Do not take KI unless instructed by public health or emergency response officials or a healthcare provider.
* KI is recommended only for people under 40 and women who are pregnant or breastfeeding.
* KI can have harmful effects when used incorrectly. Only use KI products that are approved by the U.S. FDA.

Potassium iodide (KI) is a type of iodine that is not radioactive. It can be used to help block one type of radioactive material, radioactive iodine, from being absorbed by the thyroid.

In some radiation emergencies, radioactive iodine may be released into the environment and enter the body through breathing or eating. This is known as internal contamination.

The thyroid is a gland in the neck that plays an important role in many body functions. When the thyroid absorbs high levels of radioactive iodine, it can increase the risk of thyroid cancer many years after exposure in infants, children, and young adults.

How KI protects the thyroid

KI is the stable (non-radioactive) form of iodine. They are both absorbed by the thyroid.

The thyroid cannot distinguish between stable or radioactive iodine. To protect the thyroid from radioactive iodine, a person must take KI before or shortly after being exposed to radioactive iodine to saturate the thyroid and prevent the radioactive iodine from concentrating in the thyroid.

When a person takes the right amount of KI at the right time, it can help block the thyroid from absorbing radioactive iodine. This happens because the thyroid has already absorbed the KI, and there is no room to absorb the radioactive iodine. Think of filling a jar with blue marbles (KI). If you then pour green marbles (radioactive iodine) over the jar, there will not be room and they will just spill out.

Use KI only if instructed

Do not take KI unless you are instructed by public health or emergency response officials or a healthcare provider. KI can cause harmful health effects. KI is helpful only in specific situations for certain groups of people.

KI should be used only as directed.

* Do not use table salt or foods that contain iodine as a substitute for KI. They do not help prevent internal contamination, and eating large amounts could be harmful.
* Only use KI products that have been approved by the Food and Drug Administration (FDA). Dietary supplements that contain iodine may not work to protect the thyroid and can hurt you.

Important

KI can have harmful health effects and can cause allergic reactions. Only take KI if instructed by public health or emergency response officials or a healthcare provider.

Limits of KI use

KI is most effective if taken shortly before or right after internal contamination with radioactive iodine. The effectiveness of KI also depends on how much radioactive iodine gets into the body and how quickly it is absorbed in the body.

KI is only recommended for people under 40 and women who are pregnant or breastfeeding. People with certain medical conditions, including known iodine sensitivity, should not take KI or should talk to a healthcare provider about whether they can safely take KI.

KI only offers limited protection in specific situations:

* KI protects only against radioactive iodine and does not protect against other types of radioactive materials.
* KI protects only the thyroid. KI does not protect other parts of the body.
* KI must be taken within 24 hours before or 4 hours after exposure to be most effective.
* KI is not a treatment and cannot reverse damage already done to the thyroid.
* KI may not give a person 100% thyroid protection from radioactive iodine.

Most radiation emergencies will involve other types of radioactive materials and not radioactive iodine alone. Radioactive iodine is most common in nuclear power plant incidents.

How to take KI

KI is recommended as a medical countermeasure to protect the thyroid from radioactive iodine in people under 40 and women who are pregnant or breastfeeding. This is because younger people's cells are still growing and increasing in number more quickly. This puts them at risk for developing thyroid cancer after breathing in radioactive iodine.

Adults over 40 years old have a much lower risk of developing thyroid cancer. They are also more likely to have health conditions, like problems with their thyroids, that increase the risk for harmful health effects from KI. However, officials or healthcare providers may instruct adults over 40 to consume KI if the predicted exposure is high enough to cause hypothyroidism (when the thyroid does not make enough hormones).

Breastfeeding women should consider temporarily stopping breastfeeding until evacuated from the impacted area, if possible, and safely feed your baby other ways. Radioactive iodine can be passed to infants through breast milk.

There are two U.S. FDA-approved forms of KI:

* Tablets in two strengths, 130 milligram (mg) and 65 mg. The tablets may be cut into smaller pieces for lower doses.
* Oral liquid solution available in one concentration, each milliliter (mL) containing 65 mg of KI. The solution comes in a 1 oz (30 mL) bottle with a dropper marked for 1, 0.5, and 0.25 mL dosing. For reference, 5 mL of liquid is one teaspoon. One mL would be about the size of a large drop of water.

Jai Ganesh · Dark Discussions at Cafe Infinity

2467) Cecil Frank Powell

Gist:

Work

Charged particles moving through photographic emulsions leave tracks that can be examined in the images developed afterward. Cecil Powell made improvements to this technique in order to study radiation and nuclear reactions. In 1947 he discovered that incident cosmic ray particles could react with atomic nuclei in the emulsion, creating other, short-lived particles. These particles turned out to be pi-mesons, the particles proposed by Yukawa as mediating the strong force binding protons and neutrons in nuclei.

Summary

Cecil Frank Powell (born December 5, 1903, Tonbridge, Kent, England—died August 9, 1969, Casargo, Italy) was a British physicist and winner of the Nobel Prize for Physics in 1950 for his development of the photographic method of studying nuclear processes and for the resulting discovery of the pion (pi-meson), a heavy subatomic particle. The pion proved to be the hypothetical particle proposed in 1935 by Yukawa Hideki of Japan in his theory of nuclear physics.

In 1928 Powell was appointed research assistant at the Henry Herbert Wills Physical Laboratory at the University of Bristol. He became professor of physics at Bristol in 1948 and director of the Wills Laboratory in 1964. Between 1939 and 1945 he developed the necessary techniques for using sensitive photographic emulsions to record the paths of cosmic rays. In plates exposed at the top of high mountains or sent up in high-altitude balloons, cosmic-ray interactions were recorded, and in 1947 the data revealed the existence of the pion (π+) as well as the process whereby it decays into two other particles, an antimuon (mu-meson) and a neutrino. Powell also discovered the antipion (π−) and, in 1949, the modes of decay of kaons (K-mesons).

Details

Cecil Frank Powell (5 December 1903 – 9 August 1969) was a British experimental physicist who received the Nobel Prize in Physics in 1950 for heading the team that developed the photographic method of studying nuclear processes, and for the resulting discovery of the pion (pi-meson).

Education

Cecil Frank Powell was born on 5 December 1903 in Tonbridge, England, the son of Frank Powell, a gunsmith, and Elizabeth Caroline Bisacre.

Powell was educated at a local primary school before gaining a scholarship to The Judd School. He then entered Sidney Sussex College, Cambridge, graduating in 1925 with First Class Honours in the Natural Sciences Tripos. After completing his bachelor's degree, he worked under Ernest Rutherford and C. T. R. Wilson in the Cavendish Laboratory, conducting research on condensation phenomena. He received his Ph.D. in Physics in 1927.

In 1932, Powell married Isobel Artner (1907–1995). They had two daughters, Jane and Annie.

Career and research

In 1927, Powell became a research assistant to Arthur Mannering Tyndall in the H. H. Wills Physical Laboratory at the University of Bristol. He was later appointed lecturer and, in 1948, Melville Wills Professor of Physics.[6] In 1936, he took part in a Royal Society expedition to Montserrat in the West Indies as part of a study of a damaging earthquake swarm. He appears on a stamp issued in Grenada.

During his time at Bristol University, Powell applied himself to the development of techniques for measuring the mobility of positive ions, to establishing the nature of the ions in common gases, and to the construction and use of a Walton generator to study the scattering of atomic nuclei. He also began to develop methods employing specialised photographic emulsions to facilitate the recording of the tracks of elementary particles, and in 1938 began applying this technique to the study of cosmic radiation, exposing photographic plates at high-altitude, at the tops of mountains and using specially designed balloons, collaborating in the study with Giuseppe Occhialini, Hugh Muirhead, and César Lattes. This work led in 1947 to the discovery of the pion (pi-meson), which proved to be the hypothetical particle proposed in 1935 by Hideki Yukawa in his theory of nuclear forces.

In 1950, Powell was awarded the Nobel Prize in Physics "for his development of the photographic method of studying nuclear processes and his discoveries regarding mesons made with this method." Lattes was working with him at the time of the discovery and had improved the sensitivity of the photographic emulsion. Lattes was the first to write an article describing the discovery that would lead to the Nobel Prize. Debendra Mohan Bose and Bibha Chowdhuri published three consecutive papers in Nature, but could not continue further investigation on account of "non-availability of more sensitive emulsion plates" during the war years.

Seven years after this discovery of mesons by Bose and Chowdhuri, Powell made the same discovery of pions and muons and further decay of muons to electrons… using the same technique". He acknowledged in his book, "In 1941, Bose and Chaudhuri had pointed it out that it is possible, in principle, to distinguish between the tracks of protons and mesons in an emulsion… They concluded that many of the charged particles arrested in their plates were lighter than protons, their mean mass being … the physical basis of their method was correct and their work represents the first approach to the scattering method of determining momenta of charged particles by observation of their tracks in emulsion". In fact, the measured mass of the particle by Bose and Chowdhuri was very close to the accepted value measured by Powell who used improved "full-tone" plates. From 1952, Powell was appointed director of several expeditions to Sardinia and the Po Valley, Italy, utilizing high-altitude balloon flights.

In 1955, Powell, also a member of the World Federation of Scientific Workers, added his signature to the Russell–Einstein Manifesto put forward by Bertrand Russell, Albert Einstein, and Joseph Rotblat, and was involved in preparations for the first Pugwash Conference on Science and World Affairs. As Rotblat put it, "Cecil Powell has been the backbone of the Pugwash Movement. He gave it coherence, endurance and vitality." Powell chaired the meetings of the Pugwash Continuing Committee, often standing in for Bertrand Russell, and attended meetings until 1968.

In 1961, Powell served on the Scientific Policy Committee of the European Organization for Nuclear Research (CERN).

Global policy

He was one of the signatories of the agreement to convene a convention for drafting a world constitution. As a result, for the first time in human history, a World Constituent Assembly convened to draft and adopt the Constitution for the Federation of Earth.

Death

On 9 August 1969, Powell died of a heart attack while on holiday with his wife in the Valsassina region of Italy, lodging in a house in Sanico, in the Province of Lecco.

Giuseppe Occhialini had a wooden bench built with Powell's name carved into a commemorative plaque, and then transported it to Premana, a village in the mountains above Lake Como. It was installed on the path where he died, outside the Rifugio Capanna Vittoria (now the Capanna Vittoria restaurant), on the Alpe Giumello, in Casargo. Occhialini's reason was, "...if that bench had already been there, Powell would probably have stopped to rest there."

Jai Ganesh · Jokes

Q: Why did the orange fail his driving test?
A: He kept peeling out.
* * *
Q: How many marmalade sandwiches did Paddington bear eat?
A: None he was already stuffed.
* * *
Q: What do you call an orange that takes over the world?
A: Orange Julius Caesar.
* * *
Q: Do you now why a orange is smart?
A: Because it CONCERTRATES!
* * *
Q: What do you call the ruthless movie about building a fruit empire?
A: There Will Be Blood...Oranges.
* * *

Jai Ganesh · Dark Discussions at Cafe Infinity

Comfortable Quotes - III

1. I think the actresses who are really successful are the ones who are comfortable in their own skins and still look human. - Emma Watson

2. I love wearing whatever is comfortable, and that could be something which was in trend years ago. So, I don't follow fashion. - Virat Kohli

3. I feel fine and comfortable with myself, but not because I'm beautiful. - Monica Bellucci

4. I have been learning English on the road since I started when I was 15, so it is a slow process but making some progress. Now I think I am much more comfortable with my English. However, it is difficult, still, when I speak about something that is not tennis. - Rafael Nadal

5. It is my first preference to do films with social significance. Art cinema has given me credibility and status as an actor, but commercial cinema has given me a comfortable living. - Om Puri

6. You need to do what's comfortable to you... if it doesn't suit your personality then I wouldn't try to be someone I'm not. - Michael Clarke

7. History and experience tell us that moral progress comes not in comfortable and complacent times, but out of trial and confusion. - Gerald R. Ford

8. I meet people overseas that know five languages - that the only language I'm comfortable in is English. - Bill Gates.

Jai Ganesh · This is Cool

Bone Marrow

Gist

Bone marrow is the soft, spongy, and highly vascularized tissue located in the cavities of bones—primarily the pelvis, ribs, and sternum—that serves as the body's main blood cell "factory". It produces red blood cells (oxygen transport), white blood cells (immune defense), and platelets (clotting) from hematopoietic stem cells, making it essential for life.

Bone marrow is the soft, spongy, highly vascular tissue found in the center of bones, primarily acting as the body's main blood cell factory. It contains stem cells that produce essential components: red blood cells (oxygen delivery), white blood cells (immune defense), and platelets (clotting).

Summary

Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It is composed of hematopoietic cells, marrow adipose tissue, and supportive stromal cells. In adult humans, bone marrow is primarily located in the ribs, vertebrae, sternum, and bones of the pelvis. Bone marrow comprises approximately 5% of total body mass in healthy adult humans, such that a person weighing 73 kg (161 lbs) will have around 3.7 kg (8 lbs) of bone marrow.

Human marrow produces approximately 500 billion blood cells per day, which join the systemic circulation via permeable vasculature sinusoids within the medullary cavity. All types of hematopoietic cells, including both myeloid and lymphoid lineages, are created in bone marrow; however, lymphoid cells must migrate to other lymphoid organs (e.g. thymus) in order to complete maturation.

Bone marrow transplants can be conducted to treat severe diseases of the bone marrow, including certain forms of cancer such as leukemia. Several types of stem cells are related to bone marrow. Hematopoietic stem cells in the bone marrow can give rise to hematopoietic lineage cells, and mesenchymal stem cells, which can be isolated from the primary culture of bone marrow stroma, can give rise to bone, adipose, and cartilage tissue.

Details

Bone marrow is the soft, fatty tissue inside of the bones in your body. Bone marrow contains cells that produce blood cells and platelets and it is responsible for making billions of new blood cells each day.

Overview:

What is bone marrow?

Bone marrow is the soft, fatty tissue inside of bone cavities. Components of your blood including red and white blood cells and platelets form inside of your bone marrow.

Function:

What does bone marrow do?

Bone marrow makes nearly all the components of your blood. It's responsible for creating billions of red blood cells daily, along with white blood cells and platelets. Bone marrow also stores fat that turns into energy as needed.

Can you live without bone marrow?

Bone marrow makes the components of your blood that you need to survive. Bone marrow produces red blood cells that carry oxygen, white blood cells that prevent infection and platelets that control bleeding. The absence of bone marrow can be fatal since it's an essential part of your body.

Can I donate bone marrow?

Yes, bone marrow and the healthy cells it produces are necessary for humans to live. Often, cell mutations harm healthy bone marrow cells, and a bone marrow transplant would be a treatment option for people diagnosed with blood cancers like leukemia.

A bone marrow transplant takes healthy cells from a donor and puts them into your bloodstream. The donor’s cells help your body grow healthy red and white blood cells and platelets.

Anatomy:

Where is bone marrow located?

There are three parts to the anatomy of your bones: compact bone, spongy bone and bone marrow. Compact bone is the strong, outer layer of your bones. Spongy bone makes up the ends of your bones. Bone marrow is in the center of most bones and in the end of spongy bones in your body. Bone marrow and blood vessels fill cavities in your bones, where they store fat and stem cells and produce blood cells that make your whole blood.

What does bone marrow look like?

Bone marrow is a spongy, soft tissue that resembles a jelly or jam that you would spread on toast. It comes in two colors, red and yellow. Bone marrow fills the cavities of your bones and holds cells that create red and white blood cells and platelets, which make whole blood. The color of red bone marrow is the result of red blood cell production.

What are the two types of bone marrow?

There are two types of bone marrow in your body, which are characterized by their color. Your body holds just under 6 lbs. (about 2.5 kg.) of red and yellow bone marrow.

* Red: Red bone marrow produces blood cells (hematopoiesis). Stem cells in your red bone marrow (hematopoietic stem cells) create red and white blood cells and platelets, all of which are components of your whole blood.
* Yellow: Yellow bone marrow stores fat. There are two types of stem cells in yellow bone marrow (adipocytes and mesenchymal stem cells). These cells preserve fat for energy production and develop bone, cartilage, muscles and fat cells for your body.

Red bone marrow makes up all of your bone marrow until about age seven. Yellow bone marrow gradually replaces red bone marrow as you age.

What is bone marrow made of?

Bone marrow is made of stem cells. These stem cells make red bone marrow, which creates blood cells and platelets for your blood. Yellow bone marrow consists mostly of fat and stem cells that produce bone and cartilage in your body.

Conditions and Disorders:

What are common conditions and disorders that affect bone marrow?

Directly targeting bone marrow is leukemia, which is a blood and bone marrow cancer. Leukemia forms when a cell mutation occurs in your bone marrow and mutated cells multiply out of control, reducing the production of healthy, normal cells.

Since bone marrow is the foundation for the creation of blood cells, blood-related conditions often are the result of abnormally functioning bone marrow. These conditions include:

* Multiple myeloma: Your body produces cancerous plasma cells in your bone marrow.
* Aplastic anemia: Your bone marrow doesn’t produce enough blood cells.
* Polycythemia vera: Your body makes too many red blood cells, which causes your blood to thicken.
* Myelodysplastic syndromes: A group of diseases characterized by your bone marrow not producing enough healthy blood cells (anemia).

What are common symptoms of bone marrow conditions?

Common symptoms of bone marrow conditions include:

* Bleeding easily,
* Bruising.
* Fatigue.
* Frequent infections.
* Muscle weakness.

What are common tests to check the health of my bone marrow?

There are two tests to check the health of your bone marrow and/or blood cells:

* Bone marrow aspiration: A needle removes fluid and cells from your bone marrow (bone marrow concentrate). The aspirate test identifies what cells are present in your bone marrow, verifies whether or not those cells are normal or abnormal and gives other information about the characteristics of your cells.
* Bone marrow biopsy: A large needle removes a piece of your bone marrow. The biopsy shows where, how many and the types of cells are present in your bone marrow.

Is it painful to remove my bone marrow?

For a bone marrow test or donation, you’ll receive an anesthetic, so you won't feel any pain during the procedure. After the procedure, you may feel side effects, which include aches and pain at the site of the incision. Each individual experiences pain differently, so the severity could vary from person to person. The pain may last for a few days or up to several weeks.

What are common treatments for bone marrow conditions?

Treatments for bone marrow conditions vary based on the severity and progress of the diagnosis. Treatment options include:

* Antibiotics.
* Blood transfusions.
* Bone marrow transplant.
* Chemotherapy.
* Supportive care to relieve symptoms.
* Stem cell transplant.

Care:

How do I keep my bone marrow healthy?

Bone marrow is the foundation of your bones, blood and muscles. Keeping your bone marrow healthy focuses on supporting components of your body that grow from bone marrow cells. You can keep your bone marrow healthy by:

* Eating a diet rich in protein (lean meats, fish, beans, nuts, milk, eggs).
* Taking vitamins (iron, B9, B12).
* Treating medical conditions where bone marrow abnormalities are a side effect.

Additional Information

Bone marrow is a soft, gelatinous tissue that fills the cavities of the bones. Bone marrow is either red or yellow, depending upon the preponderance of hematopoietic (red) or fatty (yellow) tissue. In humans the red bone marrow forms all of the blood cells with the exception of the lymphocytes, which are produced in the marrow and reach their mature form in the lymphoid organs. Red bone marrow also contributes, along with the liver and spleen, to the destruction of old red blood cells. Yellow bone marrow serves primarily as a storehouse for fats but may be converted to red marrow under certain conditions, such as severe blood loss or fever. At birth and until about the age of seven, all human marrow is red, as the need for new blood formation is high. Thereafter, fat tissue gradually replaces the red marrow, which in adults is found only in the vertebrae, hips, breastbone, ribs, and skull and at the ends of the long bones of the arm and leg; other cancellous, or spongy, bones and the central cavities of the long bones are filled with yellow marrow.

Red marrow consists of a delicate, highly vascular fibrous tissue containing stem cells, which differentiate into various blood cells. Stem cells first become precursors, or blast cells, of various kinds; normoblasts give rise to the red blood cells (erythrocytes), and myeloblasts become the granulocytes, a type of white blood cell (leukocyte). Platelets, small blood cell fragments involved in clotting, form from giant marrow cells called megakaryocytes. The new blood cells are released into the sinusoids, large thin-walled vessels that drain into the veins of the bone. In mammals, blood formation in adults takes place predominantly in the marrow. In lower vertebrates a number of other tissues may also produce blood cells, including the liver and the spleen.

Because the white blood cells produced in the bone marrow are involved in the body’s immune defenses, marrow transplants have been used to treat certain types of immune deficiency and hematological disorders, especially leukemia. The sensitivity of marrow to damage by radiation therapy and some anticancer drugs accounts for the tendency of these treatments to impair immunity and blood production.

Examination of the bone marrow is helpful in diagnosing certain diseases, especially those related to blood and blood-forming organs, because it provides information on iron stores and blood production. Bone marrow aspiration, the direct removal of a small amount (about 1 ml) of bone marrow, is accomplished by suction through a hollow needle. The needle is usually inserted into the hip or sternum (breastbone) in adults and into the upper part of the tibia (the larger bone of the lower leg) in children. The necessity for a bone marrow aspiration is ordinarily based on previous blood studies and is particularly useful in providing information on various stages of immature blood cells. Disorders in which bone marrow examination is of special diagnostic value include leukemia, multiple myeloma, Gaucher disease, unusual cases of anemia, and other hematological diseases.

Jai Ganesh · Science HQ

Jaundice

Gist

Jaundice is the yellowing of the skin and eyes caused by excess bilirubin in the blood, signaling underlying liver dysfunction, bile duct obstruction, or accelerated red blood cell destruction. Common causes include hepatitis, cirrhosis, gallstones, and, in newborns, immature liver function.

Jaundice is primarily caused by a buildup of bilirubin in the blood, resulting from liver dysfunction, bile duct obstruction, or rapid red blood cell breakdown. Common underlying factors include hepatitis, liver cirrhosis, gallstones, alcohol-related liver disease, and pancreatic cancer, which prevent proper processing or excretion of bilirubin.

Summary

Jaundice, also known as icterus, is a yellowish or, less frequently, greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults typically indicates the presence of underlying diseases involving abnormal heme metabolism, liver dysfunction, or biliary-tract obstruction. The prevalence of jaundice in adults is rare, while jaundice in babies is common, with an estimated 80% affected during their first week of life. The most commonly associated symptoms of jaundice are itchiness,[2] pale feces, and dark urine.

Normal levels of bilirubin in blood are below 1.0 mg/dl (17 μmol/L), while levels over 2–3 mg/dl (34–51 μmol/L) typically result in jaundice. High blood bilirubin is divided into two types: unconjugated and conjugated bilirubin.

Causes of jaundice vary from relatively benign to potentially fatal. High unconjugated bilirubin may be due to excess red blood cell breakdown, large bruises, genetic conditions such as Gilbert's syndrome, not eating for a prolonged period of time, newborn jaundice, or thyroid problems. High conjugated bilirubin may be due to liver diseases such as cirrhosis or hepatitis, infections, medications, or blockage of the bile duct, due to factors including gallstones, cancer, or pancreatitis. Other conditions can also cause yellowish skin, but are not jaundice, including carotenemia, which can develop from eating large amounts of foods containing carotene—or medications such as rifampin.

Treatment of jaundice is typically determined by the underlying cause. If a bile duct blockage is present, surgery is typically required; otherwise, management is medical. Medical management may involve treating infectious causes and stopping medication that could be contributing to the jaundice. Jaundice in newborns may be treated with phototherapy or exchanged transfusion depending on age and prematurity when the bilirubin is greater than 4–21 mg/dl (68–365 μmol/L). The itchiness may be helped by draining the gallbladder, ursodeoxycholic acid, or opioid antagonists such as naltrexone. The word jaundice is from the French jaunisse, meaning 'yellow disease'.

Details

Jaundice is a condition where your skin, the whites of your eyes and mucous membranes (like the inside of your nose and mouth) turn yellow. Many medical conditions can cause jaundice, like hepatitis, gallstones and tumors. Jaundice usually clears up once your healthcare provider treats your main medical condition.

Overview:

What is jaundice?

Jaundice (hyperbilirubinemia) is when your skin, sclera (whites of your eyes) and mucous membranes turn yellow. Jaundice occurs when your liver is unable to process bilirubin (a yellow substance made when red blood cells break down) in your blood. This can either be caused by too much red blood cell breakdown or liver injury.

How jaundice develops:

* Red blood cell breakdown: Your body regularly breaks down old red blood cells and replaces them with new ones. This breakdown process makes bilirubin.
* Bilirubin processing: Normally, your liver processes bilirubin, making it a part of bile (a bitter, greenish-brown fluid that helps digest food). Your liver then releases the bile into your digestive system.
* Too much bilirubin: Jaundice happens when your liver can’t process all the bilirubin your body makes, or if your liver has a problem releasing bilirubin.
* Yellow color: When there’s too much bilirubin in your blood, it starts to leak into tissues around your blood vessels. This leaking bilirubin makes your skin and the whites of your eyes yellow. This yellow color is a common sign of jaundice.

Possible Causes:

What causes jaundice?

Jaundice can result from a problem in any of the three phases of bilirubin:

* Before your liver processes bilirubin (prehepatic jaundice). This type of jaundice happens before your body makes bilirubin. Too much red blood cell breakdown takes over your liver’s ability to filter out bilirubin from your blood.
* During the production of bilirubin (hepatic jaundice). This type happens when your liver can’t remove enough bilirubin from your blood. Hepatic jaundice can happen if you have liver failure.
* After production of bilirubin (posthepatic jaundice). Also called obstructive jaundice, this type happens when a blockage stops bilirubin from draining into your bile ducts.

Conditions that cause jaundice include:

Prehepatic jaundice causes

* Breaking down a large hematoma (bruise) and then reabsorbing it back into your bloodstream.
* Hemolytic anemias (when blood cells are destroyed and removed from the bloodstream before their normal lifespan is over).

Hepatic jaundice causes

* Viruses, including hepatitis A, chronic hepatitis B and C, and Epstein-Barr virus infection (infectious mononucleosis).
* Alcohol-induced hepatitis.
* Autoimmune disorders.
* Rare genetic metabolic defects.
* Medicines, including penicillin, oral contraceptives, chlorpromazine (Thorazine R), estrogenic or anabolic steroids and acetaminophen toxicity.

Posthepatic jaundice causes

* Gallstones.
* Inflammation (swelling) of your gallbladder.
* Gallbladder cancer.
* Pancreatic tumor.

How do you know if you have jaundice?

You may not notice the yellow skin and sclera associated with jaundice. Your provider may find the condition when looking for something else. How serious your symptoms are depends on what causes them and how quickly or slowly they develop.

Symptoms that can be associated with jaundice include:

* Yellowish tint to your skin and the whites of your eyes.
* Fever.
* Chills.
* Pain in your belly.
* Flu-like symptoms.
* Dark-colored pee.
* Pale-colored poop.
* Being tired or confused.
* Itchy skin.
* Weight loss.

Care and Treatment:

How can my provider tell I have jaundice?

Your provider can tell if you have jaundice by measuring the bilirubin levels in your blood and seeing whether it’s the type of bilirubin related to red blood cell breakdown (unconjugated) or liver injury (conjugated). They may also check for other signs of liver disease, including:

* Bruising.
* Spider angiomas (abnormal collection of blood vessels near the surface of your skin).
* Palmar erythema (red palms and fingertips).

Your healthcare provider will also examine you to decide your liver’s size and tenderness. They may use imaging (ultrasound and CT scanning) and liver biopsy (taking a tissue sample of your liver) to better understand what’s causing your liver injury.

How is jaundice treated?

There’s no specific treatment for jaundice. But your provider can treat the cause and the jaundice should improve. They can also treat complications the condition causes. For example, if itchy skin is a problem, your provider can prescribe medication.

What are the risks of not treating jaundice?

It depends on what’s causing your jaundice. If it’s a virus, the virus could spread or become chronic. But if you have jaundice because your liver is failing, complications from your liver disease can include coma and death.

Can you prevent jaundice?

Since there are many causes of jaundice, it’s hard to find ways to prevent it. Some general tips include:

* Avoiding hepatitis infection by getting vaccinated, having safe sex, using clean needles and practicing good personal hygiene like thorough hand-washing with soap and water.
* Staying within recommended alcohol limits.
* Maintaining a weight that’s healthy for you.
* Avoiding natural and herbal supplements.
* Managing your cholesterol.

When To Call the Doctor:

When should jaundice be treated by a doctor or healthcare provider?

A healthcare provider should evaluate jaundice. It’s a sign that something’s not right with your liver. If you notice signs of jaundice, call your healthcare provider.

Additional Common Questions:

Do children get jaundice?

Jaundice is common in newborn babies. Like with adults, a buildup of bilirubin in your baby’s blood can cause jaundice. Since your baby’s liver is still developing, it can’t remove (or break down) all the bilirubin. Jaundice usually goes away on its own or providers treat it with phototherapy.

Additional Information:

What Is Jaundice?

When red blood cells die, they leave behind bilirubin, a yellow-orange pigment in the blood. The liver filters bilirubin from the bloodstream to be removed in your stool. If too much is in your system or your liver is overloaded, it causes a buildup known as hyperbilirubinemia. This causes jaundice, where your skin and the whites of your eyes look yellow.

Newborn babies often get it. About 60% have jaundice, also known as icterus, within the first couple of days after birth. Adults can get it, too, although it's less common. See a doctor right away if you think you have jaundice. It could be a symptom of a liver, blood, or gallbladder problem.

Types of Jaundice

There are four main types of jaundice, which are grouped by where the bilirubin collects in your body. A blood test can determine which type you have.

Prehepatic

If bilirubin builds up before blood enters the liver, it's known as prehepatic jaundice. This means you're breaking down red blood cells and creating more bilirubin than your liver can process.

Hepatic

If your liver isn't able to process bilirubin well, it's called hepatic jaundice.

Posthepatic

Posthepatic jaundice is when bilirubin builds up after passing through the liver and your body can't clear it quickly enough.

Obstructive jaundice

This condition is when bile isn't able to drain into your intestines because of a blocked or narrow bile or pancreatic duct. This type of jaundice has a high death rate, so it's important to catch and treat it early.

Jaundice Symptoms

Jaundice may have no symptoms. Any signs you have may depend on how quickly the condition is getting worse. Well-known symptoms are yellowing of the skin and jaundice eyes (also called scleral icterus). But there are others to watch for, including:

* Fever
* Stomach pain
* Chills
* Dark urine
* Tar- or clay-colored stools
* Flu-like symptoms
* Itchy skin
* Weight loss
* Feeling unusually irritated
* Confusion
* Abnormal drowsiness
* Bruising or bleeding easily
* Bloody vomit

How long does jaundice last in adults?

How long jaundice lasts depends on what's causing it and the treatment you need. If a medication is causing it, jaundice will fade after you stop taking it. If hepatitis is causing it, medications can be taken to treat the condition. If there is a blocked bile duct or gallstones, surgery may be required.

Jaundice Causes

Jaundice in adults is rare, but you can get it for many reasons. These include:

* Hepatitis: Liver inflammation can be caused by a virus, autoimmune disorder, alcohol or drug use, or chemical exposure. It may be short-lived (acute) or chronic, which means it lasts for at least 6 months. Long-term inflammation can damage the liver, causing jaundice.
* Alcohol-related liver disease: If you drink heavily over a long period of time – typically 8 to 10 years – you could seriously damage your liver. Two diseases in particular, alcoholic hepatitis and alcoholic cirrhosis, harm the liver.
* Other liver disease: Cirrhosis can also be caused by autoimmune diseases, genetic conditions that are passed down in your family, and hepatitis. A severe condition known as nonalcoholic steatohepatitis can cause nonalcoholic fatty liver disease. With this kind of liver disease, fat builds up in your liver along with inflammation, which damages it over time.
* Blocked bile ducts: These are thin tubes that carry a fluid called bile from your liver and gallbladder to your small intestine. If the tubes are blocked by gallstones, cancer, inflammation, or rare liver diseases, you could get jaundice.
* Pancreatic cancer: This is the 10th most common cancer in men and the ninth in women. It can block the bile duct, causing jaundice.
* Certain medicines: Drugs like acetaminophen, penicillin, birth control pills, and steroids have been linked to liver disease.
* Blood clots: If your body reabsorbs a large blot clot (hematoma) under the skin, it can increase bilirubin levels.
* Hemolytic anemias: Destroyed blood cells are sometimes removed from the bloodstream too quickly, increasing bilirubin levels.

Diagnosing Jaundice

Your doctor will ask you about your symptoms and medical history. They'll then give you a physical exam to see if there's swelling in your liver.

To get more information, your doctor will likely order blood tests to measure bilirubin and cholesterol levels and get a complete blood count (CBC). If you have jaundice, your level of bilirubin will be high. Your doctor may order other tests to find the cause of your jaundice and how severe it is, including:

* A hepatitis panel, which is a blood test that shows if you have, or have had, hepatitis. It tests for hepatitis A, hepatitis B, and hepatitis C. If there are no hepatitis antibodies in your blood, it means you don't have the condition, or you had it in the past, but your body has cleared it.
* Tests to check enzyme levels in the liver to see how well it is functioning. If enzyme levels are higher or lower than normal, it can mean you have disease or damage to the liver or bile ducts.
* Imaging, like a CT scan, ultrasound, or magnetic resonance cholangiopancreatography, a type of MRI that checks for blocked ducts near the gallbladder
* A liver biopsy, to show if you have damage to, or disease in, your liver. During the test, a small piece of your liver is removed either with a needle inserted into the belly to the liver, through a vein in your neck, or through a cut in your belly.
* Prothrombin time, which measures how long it takes for blood plasma to clot. Your blood will be taken, and a laboratory will test it to see if it clots faster or slower than the normal range (which is between 10 and 13 seconds). If it clots too slowly, that may mean there are problems with your liver.

Jaundice Treatment

In adults, jaundice itself usually isn’t treated. But your doctor will treat the condition that’s causing it.

If you have acute viral hepatitis, jaundice will go away on its own as your liver heals. If a blocked bile duct is to blame, your doctor may suggest surgery to open it. If your skin is itching, your doctor can prescribe cholestyramine to be taken by mouth. This medication is used to remove bile acids from your body, which cause itching.

Phototherapy for jaundice

Phototherapy uses a fluorescent white or blue-spectrum light that breaks down bilirubin so it can be released from the body. This treatment is used for newborns, but phototherapy has not been shown to be effective for treating jaundice in adults.

Preventing Jaundice
You may have a higher risk for jaundice if you drink too much alcohol or have hepatitis. It is also more common in people during middle age.

You can reduce your risk of jaundice through lifestyle changes like:

* Avoid herbal supplements (which can be toxic to the liver) unless recommended by your doctor
* Stop smoking
* Reduce or cut out all alcohol (the CDC recommends no more than two alcoholic drinks per day for men and one daily for women)
* Don't use intravenous drugs (drugs that go into your vein)
* Don't take more prescription medication than you are prescribed
* Get all recommended vaccines before traveling overseas
* Use safe sex practices
* Maintain a healthy weight
* Keep your cholesterol in a healthy range

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Jai Ganesh · Jai Ganesh's Puzzles

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