1.
Iron
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Iron is a chemical element with symbol Fe and atomic number 26. It is a metal in the first transition series and it is by mass the most common element on Earth, forming much of Earths outer and inner core. It is the fourth most common element in the Earths crust, like the other group 8 elements, ruthenium and osmium, iron exists in a wide range of oxidation states, −2 to +6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen, fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike the metals that form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, Iron metal has been used since ancient times, although copper alloys, which have lower melting temperatures, were used even earlier in human history. Pure iron is soft, but is unobtainable by smelting because it is significantly hardened and strengthened by impurities, in particular carbon. A certain proportion of carbon steel, which may be up to 1000 times harder than pure iron. Crude iron metal is produced in blast furnaces, where ore is reduced by coke to pig iron, further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and iron alloys formed with metals are by far the most common industrial metals because they have a great range of desirable properties. Iron chemical compounds have many uses, Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. Iron forms binary compounds with the halogens and the chalcogens, among its organometallic compounds is ferrocene, the first sandwich compound discovered. Iron plays an important role in biology, forming complexes with oxygen in hemoglobin and myoglobin. Iron is also the metal at the site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants. A human male of average height has about 4 grams of iron in his body and this iron is distributed throughout the body in hemoglobin, tissues, muscles, bone marrow, blood proteins, enzymes, ferritin, hemosiderin, and transport in plasma. The mechanical properties of iron and its alloys can be evaluated using a variety of tests, including the Brinell test, Rockwell test, the data on iron is so consistent that it is often used to calibrate measurements or to compare tests. An increase in the content will cause a significant increase in the hardness. Maximum hardness of 65 Rc is achieved with a 0. 6% carbon content, because of the softness of iron, it is much easier to work with than its heavier congeners ruthenium and osmium. Because of its significance for planetary cores, the properties of iron at high pressures and temperatures have also been studied extensively
2.
Heme
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Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as their prosthetic group, these are known as hemoproteins. Hemoproteins have diverse functions including the transportation of diatomic gases, chemical catalysis, diatomic gas detection. The heme iron serves as a source or sink of electrons during electron transfer or redox chemistry, in peroxidase reactions, the porphyrin molecule also serves as an electron source. In the transportation or detection of gases, the gas binds to the heme iron. During the detection of gases, the binding of the gas ligand to the heme iron induces conformational changes in the surrounding protein. Hemoproteins achieve their remarkable diversity by modifying the environment of the heme macrocycle within the protein matrix. For example, the ability of hemoglobin to effectively deliver oxygen to tissues is due to amino acid residues located near the heme molecule. Hemoglobin reversibly binds to oxygen in the lungs when the pH is high, when the situation is reversed, hemoglobin will release oxygen into the tissues. This phenomenon, which states that hemoglobins oxygen binding affinity is inversely proportional to both acidity and concentration of carbon dioxide, is known as the Bohr effect. There are several biologically important kinds of heme, The most common type is heme B, other important types include heme A, isolated hemes are commonly designated by capital letters while hemes bound to proteins are designated by lower case letters. Cytochrome a refers to the heme A in specific combination with membrane protein forming a portion of cytochrome c oxidase, the following carbon numbering system of porphyrins is an older numbering used by biochemists and not the 1–24 numbering system recommended by IUPAC which is shown in the table above. Heme l is the derivative of heme B which is attached to the protein of lactoperoxidase, eosinophil peroxidase. The addition of peroxide with the glutamyl-375 and aspartyl-225 of lactoperoxidase forms ester bonds between amino acid residues and the heme 1- and 5-methyl groups, respectively. Similar ester bonds with two methyl groups are thought to form in eosinophil and thyroid peroxidases. Heme l is one important characteristic of animal peroxidases, plant peroxidases incorporate heme B, lactoperoxidase and eosinophil peroxidase are protective enzymes responsible for the destruction of invading bacteria and virus. Thyroid peroxidase is the enzyme catalyzing the biosynthesis of the important thyroid hormones, because lactoperoxidase destroys invading organisms in the lungs and excrement, it is thought to be an important protective enzyme. Heme m is the derivative of heme B covalently bound at the site of myeloperoxidase. Heme m contains the two ester bonds at the heme 1- and 5-methyls as in heme l found in other mammalian peroxidases, myeloperoxidase is present in mammalian neutrophils and is responsible for the destruction of invading bacteria and viruse
3.
Hematology
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Hematology, also spelled haematology, is the branch of medicine concerned with the study, diagnosis, treatment, and prevention of diseases related to blood. Hematology includes the study of cause], such diseases might include hemophilia, blood clots, other bleeding disorders and blood cancers such as leukemia, myeloma, and lymphoma. The laboratory work that goes into the study of blood is frequently performed by a medical technologist or medical laboratory scientist, many hematologists work as hematologist-oncologists, also providing medical treatment for all types of cancer. Physicians specialized in hematology are known as hematologists or haematologists, in some institutions, hematologists also manage the hematology laboratory. Hematologists and hematopathologists generally work in conjunction to formulate a diagnosis, hematology is a distinct subspecialty of internal medicine, separate from but overlapping with the subspecialty of medical oncology
4.
Cell (biology)
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The cell is the basic structural, functional, and biological unit of all known living organisms. A cell is the smallest unit of life that can replicate independently, the study of cells is called cell biology. Cells consist of cytoplasm enclosed within a membrane, which contains many such as proteins. Organisms can be classified as unicellular or multicellular, while the number of cells in plants and animals varies from species to species, humans contain more than 10 trillion cells. Most plant and animal cells are only under a microscope. The cell was discovered by Robert Hooke in 1665, who named the unit for its resemblance to cells inhabited by Christian monks in a monastery. Cells emerged on Earth at least 3.5 billion years ago, Cells are of two types, eukaryotic, which contain a nucleus, and prokaryotic, which do not. Prokaryotes are single-celled organisms, while eukaryotes can be either single-celled or multicellular, prokaryotic cells were the first form of life on Earth, characterised by having vital biological processes including cell signaling and being self-sustaining. They are simpler and smaller than eukaryotic cells, and lack membrane-bound organelles such as the nucleus, prokaryotes include two of the domains of life, bacteria and archaea. The DNA of a prokaryotic cell consists of a chromosome that is in direct contact with the cytoplasm. The nuclear region in the cytoplasm is called the nucleoid, most prokaryotes are the smallest of all organisms ranging from 0.5 to 2.0 µm in diameter. Though most prokaryotes have both a cell membrane and a wall, there are exceptions such as Mycoplasma and Thermoplasma which only possess the cell membrane layer. The envelope gives rigidity to the cell and separates the interior of the cell from its environment, the cell wall consists of peptidoglycan in bacteria, and acts as an additional barrier against exterior forces. It also prevents the cell from expanding and bursting from osmotic pressure due to a hypotonic environment, some eukaryotic cells also have a cell wall. Inside the cell is the region that contains the genome, ribosomes. The genetic material is found in the cytoplasm. Prokaryotes can carry extrachromosomal DNA elements called plasmids, which are usually circular, linear bacterial plasmids have been identified in several species of spirochete bacteria, including members of the genus Borrelia notably Borrelia burgdorferi, which causes Lyme disease. Though not forming a nucleus, the DNA is condensed in a nucleoid, plasmids encode additional genes, such as antibiotic resistance genes
5.
Oxygen
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Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog. At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
6.
Hemoglobin
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Hemoglobin in the blood carries oxygen from the respiratory organs to the rest of the body. There it releases the oxygen to permit aerobic respiration to provide energy to power the functions of the organism in the process called metabolism, in mammals, the protein makes up about 96% of the red blood cells dry content, and around 35% of the total content. Hemoglobin has a capacity of 1.34 mL O2 per gram. The mammalian hemoglobin molecule can bind up to four oxygen molecules, Hemoglobin is involved in the transport of other gases, It carries some of the bodys respiratory carbon dioxide as carbaminohemoglobin, in which CO2 is bound to the globin protein. The molecule also carries the important regulatory molecule nitric oxide bound to a globin protein thiol group, Hemoglobin is also found outside red blood cells and their progenitor lines. Other cells that contain hemoglobin include the A9 dopaminergic neurons in the substantia nigra, macrophages, alveolar cells, in these tissues, hemoglobin has a non-oxygen-carrying function as an antioxidant and a regulator of iron metabolism. Hemoglobin and hemoglobin-like molecules are found in many invertebrates, fungi. In these organisms, hemoglobins may carry oxygen, or they may act to transport and regulate other small molecules and ions such as carbon dioxide, nitric oxide, hydrogen sulfide and sulfide. In 1825 J. F. Engelhard discovered that the ratio of Fe to protein is identical in the hemoglobins of several species, from the known atomic mass of iron he calculated the molecular mass of hemoglobin to n ×16000, the first determination of a proteins molecular mass. This hasty conclusion drew a lot of ridicule at the time from scientists who could not believe that any molecule could be that big, gilbert Smithson Adair confirmed Engelhards results in 1925 by measuring the osmotic pressure of hemoglobin solutions. The oxygen-carrying protein hemoglobin was discovered by Hünefeld in 1840, hemoglobins reversible oxygenation was described a few years later by Felix Hoppe-Seyler. In 1959, Max Perutz determined the structure of myoglobin by X-ray crystallography. This work resulted in his sharing with John Kendrew the 1962 Nobel Prize in Chemistry, the role of hemoglobin in the blood was elucidated by French physiologist Claude Bernard. The name hemoglobin is derived from the heme and globin. Each heme group contains one iron atom, that can bind one oxygen molecule through ion-induced dipole forces, the most common type of hemoglobin in mammals contains four such subunits. Hemoglobin consists of subunits, and these proteins, in turn, are folded chains of a large number of different amino acids called polypeptides. The amino acid sequence of any polypeptide created by a cell is in turn determined by the stretches of DNA called genes, in all proteins, it is the amino acid sequence that determines the proteins chemical properties and function. There is more than one gene, in humans, hemoglobin A is coded for by the genes, HBA1, HBA2
7.
Cytochrome
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Cytochromes are iron containing hemeproteins central to which are heme groups that are primarily responsible for the generation of ATP via electron transport. They are found either as monomeric proteins or as subunits of enzymatic complexes that catalyze redox reactions. Cytochromes were initially described in 1884 by MacMunn as respiratory pigments, the ultra-violet to visible spectroscopic signatures of hemes are still used to identify heme type from the reduced bis-pyridine-ligated state, i. e. the pyridine hemochrome method. The heme group is a highly conjugated ring system surrounding a metal ion, for many cytochromes, the metal ion present is that of iron, which interconverts between Fe2+ and Fe3+ states. Cytochromes are, thus, capable of performing oxidation and reduction, because the cytochromes are held within membranes in an organized way, the redox reactions are carried out in the proper sequence for maximum efficiency. The resulting transmembrane proton gradient is used to generate ATP, which is the chemical energy currency of life. ATP is consumed to drive cellular processes that require energy, several kinds of cytochrome exist and can be distinguished by spectroscopy, exact structure of the heme group, inhibitor sensitivity, and reduction potential. Three types of cytochrome are distinguished by their groups, The definition of cytochrome c is not defined in terms of the heme group. There is no cytochrome e, but there is a cytochrome f and these enzymes are primarily involved in steroidogenesis and detoxification. Scripps Database of Metalloproteins Cytochromes at the US National Library of Medicine Medical Subject Headings
8.
Enzyme
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Enzymes /ˈɛnzaɪmz/ are macromolecular biological catalysts. Enzymes accelerate, or catalyze, chemical reactions, the molecules at the beginning of the process upon which enzymes may act are called substrates and the enzyme converts these into different molecules, called products. Almost all metabolic processes in the cell need enzymes in order to occur at rates fast enough to sustain life, the set of enzymes made in a cell determines which metabolic pathways occur in that cell. The study of enzymes is called enzymology, enzymes are known to catalyze more than 5,000 biochemical reaction types. Most enzymes are proteins, although a few are catalytic RNA molecules, enzymes specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the rate of a reaction by lowering its activation energy, some enzymes can make their conversion of substrate to product occur many millions of times faster. An extreme example is orotidine 5-phosphate decarboxylase, which allows a reaction that would take millions of years to occur in milliseconds. Chemically, enzymes are like any catalyst and are not consumed in chemical reactions, enzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules, inhibitors are molecules that decrease enzyme activity, many drugs and poisons are enzyme inhibitors. An enzymes activity decreases markedly outside its optimal temperature and pH, some enzymes are used commercially, for example, in the synthesis of antibiotics. French chemist Anselme Payen was the first to discover an enzyme, diastase and he wrote that alcoholic fermentation is an act correlated with the life and organization of the yeast cells, not with the death or putrefaction of the cells. In 1877, German physiologist Wilhelm Kühne first used the term enzyme, the word enzyme was used later to refer to nonliving substances such as pepsin, and the word ferment was used to refer to chemical activity produced by living organisms. Eduard Buchner submitted his first paper on the study of yeast extracts in 1897, in a series of experiments at the University of Berlin, he found that sugar was fermented by yeast extracts even when there were no living yeast cells in the mixture. He named the enzyme that brought about the fermentation of sucrose zymase, in 1907, he received the Nobel Prize in Chemistry for his discovery of cell-free fermentation. Following Buchners example, enzymes are usually named according to the reaction they carry out, the biochemical identity of enzymes was still unknown in the early 1900s. Sumner showed that the enzyme urease was a protein and crystallized it. These three scientists were awarded the 1946 Nobel Prize in Chemistry, the discovery that enzymes could be crystallized eventually allowed their structures to be solved by x-ray crystallography. This high-resolution structure of lysozyme marked the beginning of the field of structural biology, an enzymes name is often derived from its substrate or the chemical reaction it catalyzes, with the word ending in -ase
9.
Morbidity
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A disease is a particular abnormal condition, a disorder of a structure or function, that affects part or all of an organism. The study of disease is called pathology which includes the study of cause, Disease is often construed as a medical condition associated with specific symptoms and signs. When caused by pathogens, even in the literature, the term disease is often misleadingly used in the place of its causal agent. This language habitat can cause confusion in the communication of the principle in epidemiology. Diseases can affect not only physically, but also emotionally. Death due to disease is called death by natural causes, there are four main types of disease, infectious diseases, deficiency diseases, genetic diseases, and physiological diseases. Diseases can also be classified as communicable and non-communicable, the deadliest diseases in humans are coronary artery disease, followed by cerebrovascular disease and lower respiratory infections. In many cases, terms such as disease, disorder, morbidity, there are situations, however, when specific terms are considered preferable. Disease The term disease broadly refers to any condition that impairs the normal functioning of the body, for this reason, diseases are associated with dysfunctioning of the bodys normal homeostatic processes. The term disease has both a count sense and a noncount sense, by contrast, an infection that is asymptomatic during its incubation period, but expected to produce symptoms later, is usually considered a disease. Non-infectious diseases are all other diseases, including most forms of cancer, heart disease, acquired disease disease that began at some point during ones lifetime, as opposed to disease that was already present at birth, which is congenital disease. Acquired sounds like it could mean caught via contagion, but it simply means acquired sometime after birth and it also sounds like it could imply secondary disease, but acquired disease can be primary disease. It is often, genetic and can be inherited and it can also be the result of a vertically transmitted infection from the mother such as HIV/AIDS. Genetic disease disease that is caused by genetic mutation and it is often inherited, but some mutations are random and de novo. Hereditary or inherited disease a type of disease caused by mutation that is hereditary Iatrogenic disease A disease condition caused by medical intervention. Idiopathic disease disease whose cause is unknown, as medical science has advanced, many diseases whose causes were formerly complete mysteries have been somewhat explained or even extensively explained. Bacterial infections can be primary or secondary to a viral infection or burn. Terminal disease disease with death as an inevitable result Illness Illness is generally used as a synonym for disease, however, this term is occasionally used to refer specifically to the patients personal experience of his or her disease
10.
Death
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Death is the cessation of all biological functions that sustain a living organism. Bodies of living organisms begin to decompose shortly after death, other concerns include fear of death, necrophobia, anxiety, sorrow, grief, emotional pain, depression, sympathy, compassion, solitude, or saudade. The potential for an afterlife is of concern for some humans, the word death comes from Old English deað, which in turn comes from Proto-Germanic *dauthuz. This comes from the Proto-Indo-European stem *dheu- meaning the Process, act, when a person has died, it is also said they have passed away, passed on, expired, or are gone, among numerous other socially accepted, religiously specific, slang, and irreverent terms. Bereft of life, the person is then a corpse, cadaver, a body, a set of remains, and when all flesh has rotted away. The terms carrion and carcass can also be used, though more often connote the remains of non-human animals. As a polite reference to a person, it has become common practice to use the participle form of decease, as in the deceased. The ashes left after a cremation are sometimes referred to by the neologism cremains, senescence refers to a scenario when a living being is able to survive all calamities, but eventually dies due to causes relating to old age. Almost all animals who survive external hazards to their biological functioning eventually die from biological aging, some organisms experience negligible senescence, even exhibiting biological immortality. These include the jellyfish Turritopsis dohrnii, the hydra, and the planarian, unnatural causes of death include suicide and homicide. From all causes, roughly 150,000 people die around the world each day, physiological death is now seen as a process, more than an event, conditions once considered indicative of death are now reversible. Where in the process a dividing line is drawn between life and death depends on factors beyond the presence or absence of vital signs, in general, clinical death is neither necessary nor sufficient for a determination of legal death. A patient with working heart and lungs determined to be dead can be pronounced legally dead without clinical death occurring. As scientific knowledge and medicine advance, formulating a precise definition of death becomes more difficult. The concept of death is a key to understanding of the phenomenon. There are many approaches to the concept. For example, brain death, as practiced in medical science, One of the challenges in defining death is in distinguishing it from life. As a point in time, death would seem to refer to the moment at which life ends, determining when death has occurred requires drawing precise conceptual boundaries between life and death
11.
Blood plasma
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Blood plasma is a straw coloured liquid component of blood that normally holds the blood cells in whole blood in suspension, this makes plasma the extracellular matrix of blood cells. It makes up about 55% of the total blood volume. It is the fluid part of extracellular fluid. It is mostly water, and contains dissolved proteins, glucose, clotting factors, electrolytes, hormones, carbon dioxide, Plasma also serves as the protein reserve of the human body. It plays a role in an intravascular osmotic effect that keeps electrolytes in balanced form and protects the body from infection. Blood plasma is prepared by spinning a tube of fresh blood containing an anticoagulant in a centrifuge until the blood fall to the bottom of the tube. The blood plasma is then poured or drawn off, Blood plasma has a density of approximately 1025 kg/m3, or 1.025 g/ml. Blood serum is blood plasma without clotting factors, in other words, plasmapheresis is a medical therapy that involves blood plasma extraction, treatment, and reintegration. Fresh frozen plasma is on the WHO Model List of Essential Medicines, Blood plasma volume may be expanded by or drained to extravascular fluid when there are changes in Starling forces across capillary walls. For example, when blood pressure drops in circulatory shock, Starling forces drive fluid into the interstitium, standing still for a prolonged period will cause an increase in transcapillary hydrostatic pressure. As a result, approximately 12% of blood plasma volume will cross into the extravascular compartment and this causes an increase in hematocrit, serum total protein, blood viscosity and, as a result of increased concentration of coagulation factors, it causes orthostatic hypercoagulability. The use of plasma as a substitute for whole blood and for transfusion purposes was proposed in March 1918, in the correspondence columns of the British Medical Journal. Dried plasmas in powder or strips of material format were developed, prior to the United States involvement in the war, liquid plasma and whole blood were used. The Blood for Britain program during the early 1940s was quite successful based on Charles Drews contribution, a large project began in August 1940 to collect blood in New York City hospitals for the export of plasma to Britain. Drew was appointed supervisor of the Plasma for Britain project. His notable contribution at this time was to transform the test tube methods of many blood researchers into the first successful mass production techniques. Nonetheless, the decision was made to develop a dried plasma package for the forces as it would reduce breakage and make the transportation, packaging. The resulting dried plasma package came in two tin cans containing 400 cc bottles, one bottle contained enough distilled water to reconstitute the dried plasma contained within the other bottle
12.
Transferrin
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Transferrins are iron-binding blood plasma glycoproteins that control the level of free iron in biological fluids. Human transferrin is encoded by the TF gene, Transferrin glycoproteins bind iron tightly, but reversibly. Although iron bound to transferrin is less than 0. 1% of total body iron, Transferrin has a molecular weight of around 80 KDa and contains two specific high-affinity Fe binding sites. The affinity of transferrin for Fe is extremely high but decreases progressively with decreasing pH below neutrality, when not bound to iron, transferrin is known as apotransferrin. The pH of the vesicle is reduced by ion pumps to about 5.5. The receptor with its ligand bound transferrin is then transported through the cycle back to the cell surface. Each transferrin molecule has the ability to carry two iron ions in the ferric form, the gene coding for transferrin in humans is located in chromosome band 3q21. Medical professionals may check serum transferrin level in iron deficiency and in iron overload disorders such as hemochromatosis, in humans, transferrin consists of a polypeptide chain containing 679 amino acids and two carbohydrate chains. The protein is composed of helices and beta sheets that form two domains. The N- and C- terminal sequences are represented by globular lobes, the amino acids which bind the iron ion to the transferrin are identical for both lobes, two tyrosines, one histidine, and one aspartic acid. For the iron ion to bind, an anion is required, Transferrin also has a transferrin iron-bound receptor, it is a disulfide-linked homodimer. In humans, each consists of 760 amino acids. It enables ligand bonding to the transferrin, as each monomer can bind to one or two atoms of iron, each monomer consists of three domains, the protease, the helical, and the apical domains. The shape of a transferrin receptor resembles a butterfly based on the intersection of three clearly shaped domains, the liver is the main site of transferrin synthesis but other tissues and organs, including the brain, also produce transferrin. The main role of transferrin is to deliver iron from absorption centers in the duodenum, Transferrin plays a key role in areas where erythropoiesis and active cell division occur. The receptor helps maintain iron homeostasis in the cells by controlling iron concentrations, Transferrin is also associated with the innate immune system. It is found in the mucosa and binds iron, thus creating an environment low in iron that impedes bacterial survival in a process called iron withholding. The level of transferrin decreases in inflammation, Transferrin and its receptor have been shown to diminish tumour cells when the receptor is used to attract antibodies
13.
Human iron metabolism
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Human iron metabolism is the set of chemical reactions maintaining human homeostasis of iron at both the systemic and cellular level. The control of this necessary but potentially toxic metal is an important part of many aspects of human health, hematologists have been especially interested in systemic iron metabolism because iron is essential for red blood cells, where most of the human bodys iron is contained. Understanding iron metabolism is also important for understanding diseases of iron overload, such as hereditary hemochromatosis, iron is an essential bioelement for most forms of life, from bacteria to mammals. Its importance lies in its ability to mediate electron transfer, in the ferrous state, iron acts as an electron donor, while in the ferric state it acts as an acceptor. Thus, iron plays a role in the catalysis of enzymatic reactions that involve electron transfer. Proteins can contain iron as part of different cofactors, such as clusters and heme groups. Human cells require iron in order to obtain energy as ATP from a process known as cellular respiration. Iron is present in the clusters and heme groups of the electron transport chain proteins that generate a proton gradient that allows ATP synthase to synthesize ATP. Heme groups are part of hemoglobin, a found in red blood cells that serves to transport oxygen from the lungs to the tissues. Heme groups are present in myoglobin to store and diffuse oxygen in muscle cells. The human body needs iron for oxygen transport, oxygen is required for the functioning and survival of nearly all cell types. Oxygen is transported from the lungs to the rest of the bound to the heme group of hemoglobin in erythrocytes. In muscles cells, iron binds myoglobin, which regulates its release and its ability to donate and accept electrons means that it can catalyze the conversion of hydrogen peroxide into free radicals. Free radicals can cause damage to a variety of cellular structures. Iron bound to proteins or cofactors such as heme is safe, also, there are virtually no truly free iron ions in the cell, since they readily form complexes with organic molecules. However, some of the iron is bound to low-affinity complexes. Iron in such complexes can cause damage as described above, to prevent that kind of damage, all life forms that use iron bind the iron atoms to proteins. This binding allows cells to benefit from iron while also limiting its ability to do harm, in mammalian cells, intracellular labile iron concentrations are typically smaller than 1 micromolar, less than 5 percent of total cellular iron
14.
Red blood cell
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RBCs take up oxygen in the lungs, or gills of fish, and release it into tissues while squeezing through the bodys capillaries. The cytoplasm of erythrocytes is rich in hemoglobin, a biomolecule that can bind oxygen and is responsible for the red color of the cells. In humans, mature red cells are flexible and oval biconcave disks. They lack a nucleus and most organelles, in order to accommodate maximum space for hemoglobin, they can be viewed as sacks of hemoglobin. Approximately 2.4 million new erythrocytes are produced per second in human adults, the cells develop in the bone marrow and circulate for about 100–120 days in the body before their components are recycled by macrophages. Each circulation takes about 60 seconds, approximately a quarter of the cells in the human body are red blood cells. Nearly half of the volume is red blood cells. Red blood cells are known as RBCs, red cells, red blood corpuscles, haematids. Packed red blood cells are red blood cells that have donated, processed. Almost all vertebrates, including all mammals and humans, have red blood cells, red blood cells are cells present in blood in order to transport oxygen. The only known vertebrates without red blood cells are the crocodile icefish, they live in very cold water. While they no longer use hemoglobin, remnants of hemoglobin genes can be found in their genome, oxygen can easily diffuse through the red blood cells cell membrane. Myoglobin, a related to hemoglobin, acts to store oxygen in muscle cells. The color of red cells is due to the heme group of hemoglobin. However, blood can appear bluish when seen through the vessel wall, pulse oximetry takes advantage of the hemoglobin color change to directly measure the arterial blood oxygen saturation using colorimetric techniques. Hemoglobin also has a high affinity for carbon monoxide, forming carboxyhemoglobin which is a very bright red in color. Flushed, confused patients with a reading of 100% on pulse oximetry are sometimes found to be suffering from carbon monoxide poisoning. The red blood cells of mammals are typically shaped as disks, flattened and depressed in the center, with a dumbbell-shaped cross section
15.
Disability-adjusted life year
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The disability-adjusted life year is a measure of overall disease burden, expressed as the number of years lost due to ill-health, disability or early death. It was developed in the 1990s as a way of comparing the overall health, the DALY is becoming increasingly common in the field of public health and health impact assessment. It extends the concept of years of life lost due to premature death. to include equivalent years of healthy life lost by virtue of being in states of poor health or disability. In so doing, mortality and morbidity are combined into a single, the disability-adjusted life year is a societal measure of the disease or disability burden in populations. DALYs are calculated by combining measures of life expectancy as well as the quality of life during a burdensome disease or disability for a population. DALYs are related to the quality-adjusted life year measure, however QALYs only measure the benefit with and without medical intervention, also, QALYs tend to be an individual measure, and not a societal measure. Traditionally, health liabilities were expressed using one measure, the years of life lost due to dying early, a medical condition that did not result in dying younger than expected was not counted. The years lost due to disability component measures the burden of living with a disease or disability, one DALY, therefore, is equal to one year of healthy life lost. How much a medical condition affects a person is called the disability weight and this is determined by disease or disability and does not vary with age. Examples of the disability weight are shown on the right, some of these are short term and the long-term weights may be different. In the GBD terminology, the disability is used broadly to refer to departures from optimal health in any of the important domains of health. At the population level, the burden as measured by DALYs is calculated by adding YLL to YLD. YLL uses the life expectancy at the time of death, there is also a prevalence based calculation for YLD. Premature death is calculated by YLL = N x L, where N = number of deaths due to condition, Japanese life expectancy statistics are used as the standard for measuring premature death, as the Japanese have the longest life expectancies. A crucial distinction among DALY studies has been the use of age-weighting, there are two components to this differential accounting of time, age-weighting and time-discounting. Age-weighting is based on the theory of human capital, commonly, years lived as a young adult are valued more highly than years spent as a young child or older adult, as these are years of peak productivity. Age-weighting receives considerable criticism for valuing young adults at the expense of children, some criticize, while others rationalize, this as reflecting societys interest in productivity and receiving a return on its investment in raising children. This age-weighting function is by no means a universal methodology in HALY studies, cost-effectiveness studies using QALYs, for example, do not discount time at different ages differently
16.
Immune system
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The immune system is a host defense system comprising many biological structures and processes within an organism that protects against disease. To function properly, a system must detect a wide variety of agents, known as pathogens, from viruses to parasitic worms. In many species, the system can be classified into subsystems, such as the innate immune system versus the adaptive immune system. In humans, the barrier, blood–cerebrospinal fluid barrier, and similar fluid–brain barriers separate the peripheral immune system from the neuroimmune system. Even simple unicellular organisms such as bacteria possess a rudimentary immune system in the form of enzymes that protect against bacteriophage infections, other basic immune mechanisms evolved in ancient eukaryotes and remain in their modern descendants, such as plants and invertebrates. These mechanisms include phagocytosis, antimicrobial peptides called defensins, and the complement system, jawed vertebrates, including humans, have even more sophisticated defense mechanisms, including the ability to adapt over time to recognize specific pathogens more efficiently. Adaptive immunity creates immunological memory after a response to a specific pathogen. This process of acquired immunity is the basis of vaccination, disorders of the immune system can result in autoimmune diseases, inflammatory diseases and cancer. Immunodeficiency occurs when the system is less active than normal. In humans, immunodeficiency can either be the result of a disease such as severe combined immunodeficiency, acquired conditions such as HIV/AIDS. In contrast, autoimmunity results from an immune system attacking normal tissues as if they were foreign organisms. Common autoimmune diseases include Hashimotos thyroiditis, rheumatoid arthritis, diabetes mellitus type 1, immunology covers the study of all aspects of the immune system. Immunology is a science that examines the structure and function of the immune system and it originates from medicine and early studies on the causes of immunity to disease. The earliest known reference to immunity was during the plague of Athens in 430 BC, thucydides noted that people who had recovered from a previous bout of the disease could nurse the sick without contracting the illness a second time. In the 18th century, Pierre-Louis Moreau de Maupertuis made experiments with scorpion venom and observed that certain dogs and this and other observations of acquired immunity were later exploited by Louis Pasteur in his development of vaccination and his proposed germ theory of disease. Pasteurs theory was in opposition to contemporary theories of disease. It was not until Robert Kochs 1891 proofs, for which he was awarded a Nobel Prize in 1905, viruses were confirmed as human pathogens in 1901, with the discovery of the yellow fever virus by Walter Reed. Immunology made an advance towards the end of the 19th century, through rapid developments, in the study of humoral immunity
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Platelet
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Platelets, also called thrombocytes, are a component of blood whose function is to stop bleeding by clumping and clotting blood vessel injuries. Platelets have no nucleus, they are fragments of cytoplasm that are derived from the megakaryocytes of the bone marrow. These unactivated platelets are biconvex discoid structures, 2–3 µm in greatest diameter, platelets are found only in mammals, whereas in other animals thrombocytes circulate as intact mononuclear cells. On a stained blood smear, platelets appear as purple spots. The smear is used to examine platelets for size, shape, qualitative number, the ratio of platelets to red blood cells in a healthy adult is 1,10 to 1,20. The main function of platelets is to contribute to hemostasis, the process of stopping bleeding at the site of interrupted endothelium and they gather at the site and unless the interruption is physically too large, they plug the hole. First, platelets attach to substances outside the interrupted endothelium, adhesion, second, they change shape, turn on receptors and secrete chemical messengers, activation. Third, they connect to each other through receptor bridges, aggregation, formation of this platelet plug is associated with activation of the coagulation cascade with resultant fibrin deposition and linking. These processes may overlap, the spectrum is from a predominantly platelet plug, or white clot to a predominantly fibrin clot, the final result is the clot. Some would add the subsequent clot retraction and platelet inhibition as fourth and fifth steps to the completion of the process, low platelet concentration is thrombocytopenia and is due to either decreased production or increased destruction. Elevated platelet concentration is thrombocytosis and is either congenital, reactive, or due to unregulated production, a disorder of platelet function is a thrombocytopathy. An arterial thrombus may partially obstruct blood flow, causing downstream ischemia, or may completely obstruct it, george Gulliver in 1841 drew pictures of platelets using the twin lens microscope invented in 1830 by Joseph Jackson Lister. This microscope improved resolution sufficiently to make it possible to see platelets for the first time, william Addison in 1842 drew pictures of a platelet-fibrin clot. Lionel Beale in 1864 was the first to publish a drawing showing platelets, max Schultze in 1865 described what he called spherules, which he noted were much smaller than red blood cells, occasionally clumped, and were sometimes found in collections of fibrin material. Queens College, Birmingham physician Dr Richard Hill Norris was the first to describe the action of platelets in 1880, giulio Bizzozero in 1882 studied the blood of amphibians microscopically in vivo. He named Schultzs spherules piastrine, little plates, william Osler observed them and, in published lectures in 1886, called them a third corpuscle and a blood plaque and described them as a colorless protoplasmic disc. Thrombocytes are cells found in the blood of non-mammalian vertebrates and they are the functional equivalents of platelets, but circulate as intact mononuclear cells, and are not simply cytoplasmic fragments of bone marrow megakaryocytes. In some contexts, the thrombus is used interchangeably with the word clot
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Menstrual bleeding
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The menstrual cycle is the regular natural change that occurs in the female reproductive system that makes pregnancy possible. The cycle is required for the production of ovocytes, and for the preparation of the uterus for pregnancy, up to 80% of women report having some symptoms during the one to two weeks prior to menstruation. Common symptoms include acne, tender breasts, bloating, feeling tired, irritability and these symptoms interfere with normal life and therefore qualify as premenstrual syndrome in 20 to 30% of women. In 3 to 8%, they are severe, the first period usually begins between twelve and fifteen years of age, a point in time known as menarche. They may occasionally start as early as eight, and this onset may still be normal, the average age of the first period is generally later in the developing world and earlier in developed world. The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women and 21 to 35 days in adults, menstruation stops occurring after menopause which usually occurs between 45 and 55 years of age. Bleeding usually lasts around 2 to 7 days, the menstrual cycle is governed by hormonal changes. These changes can be altered by using hormonal birth control to prevent pregnancy, each cycle can be divided into three phases based on events in the ovary or in the uterus. The ovarian cycle consists of the phase, ovulation, and luteal phase whereas the uterine cycle is divided into menstruation, proliferative phase. Stimulated by gradually increasing amounts of estrogen in the phase, discharges of blood flow stop. Follicles in the ovary begin developing under the influence of an interplay of hormones. Approximately mid-cycle, 24–36 hours after the luteinizing hormone surges, the dominant follicle releases an ovocyte, under the influence of progesterone, the uterine lining changes to prepare for potential implantation of an embryo to establish a pregnancy. If implantation does not occur within two weeks, the corpus luteum will involute, causing a sharp drop in levels of both progesterone and estrogen. The hormone drop causes the uterus to shed its lining in a process termed menstruation, menstruation also occurs in some other animals including shrews, bats, and other primates such as apes and monkeys. The average age of menarche is 12–15 and they may occasionally start as early as eight, and this onset may still be normal. This first period occurs later in the developing world than the developed world. The average age of menarche is approximately 12.5 years in the United States,12.7 in Canada,12.9 in the UK and 13.1 years in Iceland, factors such as genetics, diet and overall health can affect timing. The cessation of menstrual cycles at the end of a reproductive period is termed menopause
. PMID 26205818.