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57-420: Mecasermin has a biological half-life of about 5.8 hours in children with severe primary IGF-1 deficiency. A related medication is mecasermin rinfabate (brand name Iplex), which is a combination of mecasermin (rhIGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), and insulin-like growth factor binding protein acid labile subunit (IGFALS) as a ternary complex . The complex serves to prolong

114-724: A blood bank . There are many different blood types in humans, the ABO blood group system , and the Rhesus blood group system being the most important. Transfusion of blood of an incompatible blood group may cause severe, often fatal, complications, so crossmatching is done to ensure that a compatible blood product is transfused. Other blood products administered intravenously are platelets, blood plasma, cryoprecipitate, and specific coagulation factor concentrates. Many forms of medication (from antibiotics to chemotherapy ) are administered intravenously, as they are not readily or adequately absorbed by

171-574: A blood transfusion, because the metabolism of transfused red blood cells does not restart immediately after a transfusion. In modern evidence-based medicine , bloodletting is used in management of a few rare diseases, including hemochromatosis and polycythemia . However, bloodletting and leeching were common unvalidated interventions used until the 19th century, as many diseases were incorrectly thought to be due to an excess of blood, according to Hippocratic medicine. English blood ( Old English blod ) derives from Germanic and has cognates with

228-424: A decay rate arises from a first-order reaction where the rate of elimination is proportional to the amount of the substance: The half-life for this process is Alternatively, half-life is given by where λ z is the slope of the terminal phase of the time–concentration curve for the substance on a semilogarithmic scale. Half-life is determined by clearance (CL) and volume of distribution (V D ) and

285-411: A different biological half-life ( physiologically-based pharmacokinetic modelling ). Attempts to remove a substance from the whole organism may have the effect of increasing the burden present in one part of the organism. For instance, if a person who is contaminated with lead is given EDTA in a chelation therapy , then while the rate at which lead is lost from the body will be increased, the lead within

342-426: A pH below 7.35 is too acidic , whereas blood pH above 7.45 is too basic. A pH below 6.9 or above 7.8 is usually lethal. Blood pH, partial pressure of oxygen (pO 2 ) , partial pressure of carbon dioxide (pCO 2 ) , and bicarbonate (HCO 3 ) are carefully regulated by a number of homeostatic mechanisms , which exert their influence principally through the respiratory system and the urinary system to control

399-537: A similar range of meanings in all other Germanic languages (e.g. German Blut , Swedish blod , Gothic blōþ ). There is no accepted Indo-European etymology. Robin Fåhræus (a Swedish physician who devised the erythrocyte sedimentation rate ) suggested that the Ancient Greek system of humorism , wherein the body was thought to contain four distinct bodily fluids (associated with different temperaments), were based upon

456-436: A substance to halve ( plasma half-life ) its steady-state when circulating in the full blood of an organism . This measurement is useful in medicine, pharmacology and pharmacokinetics because it helps determine how much of a drug needs to be taken and how frequently it needs to be taken if a certain average amount is needed constantly. By contrast, the stability of a substance in plasma is described as plasma stability. This

513-408: A week to take full effect. For this reason, drugs with a long half-life (e.g., amiodarone , elimination t ⁠ 1 / 2 ⁠ of about 58 days) are usually started with a loading dose to achieve their desired clinical effect more quickly. Many drugs follow a biphasic elimination curve — first a steep slope then a shallow slope: The longer half-life is called the terminal half-life and

570-423: Is blood plasma , a fluid that is the blood's liquid medium, which by itself is straw-yellow in color. The blood plasma volume totals of 2.7–3.0 liters (2.8–3.2 quarts) in an average human. It is essentially an aqueous solution containing 92% water, 8% blood plasma proteins , and trace amounts of other materials. Plasma circulates dissolved nutrients, such as glucose , amino acids , and fatty acids (dissolved in

627-461: Is arterial or venous blood). Most of it (about 70%) is converted to bicarbonate ions HCO − 3 by the enzyme carbonic anhydrase in the red blood cells by the reaction CO 2 + H 2 O → H 2 CO 3 → H + HCO − 3 ; about 7% is dissolved in the plasma; and about 23% is bound to hemoglobin as carbamino compounds. Hemoglobin, the main oxygen-carrying molecule in red blood cells, carries both oxygen and carbon dioxide. However,

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684-418: Is associated with a large number of beliefs. One of the most basic is the use of blood as a symbol for family relationships through birth/parentage; to be "related by blood" is to be related by ancestry or descendence, rather than marriage. This bears closely to bloodlines , and sayings such as " blood is thicker than water " and " bad blood ", as well as " Blood brother ". Blood is given particular emphasis in

741-402: Is between one and four months. This can be shortened by feeding the person prussian blue . The prussian blue in the digestive system acts as a solid ion exchanger which absorbs the caesium while releasing potassium ions. For some substances, it is important to think of the human or animal body as being made up of several parts, each with its own affinity for the substance, and each part with

798-440: Is bright red, because carbon monoxide causes the formation of carboxyhemoglobin . In cyanide poisoning, the body cannot use oxygen, so the venous blood remains oxygenated, increasing the redness. There are some conditions affecting the heme groups present in hemoglobin that can make the skin appear blue – a symptom called cyanosis . If the heme is oxidized, methemoglobin , which is more brownish and cannot transport oxygen,

855-407: Is circulated around the body through blood vessels by the pumping action of the heart . In humans, blood is pumped from the strong left ventricle of the heart through arteries to peripheral tissues and returns to the right atrium of the heart through veins . It then enters the right ventricle and is pumped through the pulmonary artery to the lungs and returns to the left atrium through

912-688: Is composed of blood cells suspended in blood plasma . Plasma, which constitutes 55% of blood fluid, is mostly water (92% by volume), and contains proteins , glucose , mineral ions , and hormones . The blood cells are mainly red blood cells (erythrocytes), white blood cells (leukocytes), and (in mammals) platelets (thrombocytes). The most abundant cells are red blood cells. These contain hemoglobin , which facilitates oxygen transport by reversibly binding to it, increasing its solubility. Jawed vertebrates have an adaptive immune system , based largely on white blood cells. White blood cells help to resist infections and parasites. Platelets are important in

969-480: Is dangerous to health, and severe hypoxia (saturations less than 30%) may be rapidly fatal. A fetus , receiving oxygen via the placenta , is exposed to much lower oxygen pressures (about 21% of the level found in an adult's lungs), so fetuses produce another form of hemoglobin with a much higher affinity for oxygen ( hemoglobin F ) to function under these conditions. CO 2 is carried in blood in three different ways. (The exact percentages vary depending whether it

1026-485: Is essential to ensure accurate analysis of drugs in plasma and for drug discovery . The relationship between the biological and plasma half-lives of a substance can be complex depending on the substance in question, due to factors including accumulation in tissues, protein binding , active metabolites, and receptor interactions. The biological half-life of water in a human is about 7 to 14 days. It can be altered by behavior. Drinking large amounts of alcohol will reduce

1083-426: Is formed. In the rare condition sulfhemoglobinemia , arterial hemoglobin is partially oxygenated, and appears dark red with a bluish hue. Veins close to the surface of the skin appear blue for a variety of reasons. However, the factors that contribute to this alteration of color perception are related to the light-scattering properties of the skin and the processing of visual input by the visual cortex , rather than

1140-436: Is free to bind oxygen, and fewer oxygen molecules can be transported throughout the blood. This can cause suffocation insidiously. A fire burning in an enclosed room with poor ventilation presents a very dangerous hazard, since it can create a build-up of carbon monoxide in the air. Some carbon monoxide binds to hemoglobin when smoking tobacco. Blood for transfusion is obtained from human donors by blood donation and stored in

1197-461: Is in equilibrium with lymph , which is continuously formed in tissues from blood by capillary ultrafiltration. Lymph is collected by a system of small lymphatic vessels and directed to the thoracic duct , which drains into the left subclavian vein , where lymph rejoins the systemic blood circulation. Blood circulation transports heat throughout the body, and adjustments to this flow are an important part of thermoregulation . Increasing blood flow to

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1254-561: Is known as the Haldane effect , and is important in the transport of carbon dioxide from the tissues to the lungs. A rise in the partial pressure of CO 2 or a lower pH will cause offloading of oxygen from hemoglobin, which is known as the Bohr effect . Some oxyhemoglobin loses oxygen and becomes deoxyhemoglobin. Deoxyhemoglobin binds most of the hydrogen ions as it has a much greater affinity for more hydrogen than does oxyhemoglobin. In mammals, blood

1311-410: Is limited. Hence the removal of a large concentration of alcohol from blood may follow zero-order kinetics . Also the rate-limiting steps for one substance may be in common with other substances. For instance, the blood alcohol concentration can be used to modify the biochemistry of methanol and ethylene glycol . In this way the oxidation of methanol to the toxic formaldehyde and formic acid in

1368-511: Is oxygenated and dark red when it is deoxygenated . Medical terms related to blood often begin with hemo- , hemato- , haemo- or haemato- from the Greek word αἷμα ( haima ) for "blood". In terms of anatomy and histology , blood is considered a specialized form of connective tissue , given its origin in the bones and the presence of potential molecular fibers in the form of fibrinogen . Blood performs many important functions within

1425-488: Is produced predominantly by the liver , while hormones are produced by the endocrine glands and the watery fraction is regulated by the hypothalamus and maintained by the kidney . Healthy erythrocytes have a plasma life of about 120 days before they are degraded by the spleen , and the Kupffer cells in the liver. The liver also clears some proteins, lipids, and amino acids. The kidney actively secretes waste products into

1482-428: Is the time taken for concentration of a biological substance (such as a medication ) to decrease from its maximum concentration ( C max ) to half of C max in the blood plasma . It is denoted by the abbreviation t 1 2 {\displaystyle t_{\frac {1}{2}}} . This is used to measure the removal of things such as metabolites , drugs , and signalling molecules from

1539-529: The acid–base balance and respiration, which is called compensation. An arterial blood gas test measures these. Plasma also circulates hormones transmitting their messages to various tissues. The list of normal reference ranges for various blood electrolytes is extensive. Human blood is typical of that of mammals, although the precise details concerning cell numbers, size, protein structure , and so on, vary somewhat between species. In non-mammalian vertebrates, however, there are some key differences: Blood

1596-483: The central nervous system in humans when given via this route. In contrast to peripheral administration, when administered intranasally via a nasal spray, oxytocin reliably crosses the blood–brain barrier and exhibits psychoactive effects in humans. In addition, unlike the case of peripheral administration, intranasal oxytocin has a central duration of at least 2.25 hours and as long as 4 hours. In likely relation to this fact, endogenous oxytocin concentrations in

1653-405: The clotting of blood. Blood is circulated around the body through blood vessels by the pumping action of the heart . In animals with lungs , arterial blood carries oxygen from inhaled air to the tissues of the body, and venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled. Blood is bright red when its hemoglobin

1710-428: The erectile tissue in the penis and clitoris . Another example of a hydraulic function is the jumping spider , in which blood forced into the legs under pressure causes them to straighten for a powerful jump, without the need for bulky muscular legs. Hemoglobin is the principal determinant of the color of blood ( hemochrome ). Each molecule has four heme groups, and their interaction with various molecules alters

1767-482: The pulmonary veins . Blood then enters the left ventricle to be circulated again. Arterial blood carries oxygen from inhaled air to all of the cells of the body, and venous blood carries carbon dioxide, a waste product of metabolism by cells , to the lungs to be exhaled. However, one exception includes pulmonary arteries, which contain the most deoxygenated blood in the body, while the pulmonary veins contain oxygenated blood. Additional return flow may be generated by

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1824-479: The urine . About 98.5% of the oxygen in a sample of arterial blood in a healthy human breathing air at sea-level pressure is chemically combined with the hemoglobin . About 1.5% is physically dissolved in the other blood liquids and not connected to hemoglobin. The hemoglobin molecule is the primary transporter of oxygen in mammals and many other species. Hemoglobin has an oxygen binding capacity between 1.36 and 1.40 ml O 2 per gram hemoglobin, which increases

1881-507: The CO 2 bound to hemoglobin does not bind to the same site as oxygen. Instead, it combines with the N-terminal groups on the four globin chains. However, because of allosteric effects on the hemoglobin molecule, the binding of CO 2 decreases the amount of oxygen that is bound for a given partial pressure of oxygen. The decreased binding to carbon dioxide in the blood due to increased oxygen levels

1938-544: The action of mecasermin in the human body; the half-life of mecasermin when provided as this complex is 13.4 hours in individuals with severe primary IGF-1 deficiency. Mecasermin therapy has been also shown to be beneficial in other conditions not related to growth failure, including diabetes mellitus and anorexia nervosa . This hormonal preparation article is a stub . You can help Misplaced Pages by expanding it . Biological half-life Biological half-life ( elimination half-life , pharmacological half-life )

1995-483: The actual color of the venous blood. Skinks in the genus Prasinohaema have green blood due to a buildup of the waste product biliverdin . Substances other than oxygen can bind to hemoglobin; in some cases, this can cause irreversible damage to the body. Carbon monoxide, for example, is extremely dangerous when carried to the blood via the lungs by inhalation, because carbon monoxide irreversibly binds to hemoglobin to form carboxyhemoglobin, so that less hemoglobin

2052-399: The biological half-life of water in the body. This has been used to decontaminate patients who are internally contaminated with tritiated water . The basis of this decontamination method is to increase the rate at which the water in the body is replaced with new water. The removal of ethanol (drinking alcohol) through oxidation by alcohol dehydrogenase in the liver from the human body

2109-473: The blood or bound to plasma proteins), and removes waste products, such as carbon dioxide , urea , and lactic acid . Other important components include: The term serum refers to plasma from which the clotting proteins have been removed. Most of the proteins remaining are albumin and immunoglobulins . Blood pH is regulated to stay within the narrow range of 7.35 to 7.45, making it slightly basic (compensation). Extra-cellular fluid in blood that has

2166-441: The body tends to relocate into the brain where it can do the most harm. Some substances may have different half-lives in different parts of the body. For example, oxytocin has a half-life of typically about three minutes in the blood when given intravenously . Peripherally administered (e.g. intravenous) peptides like oxytocin cross the blood-brain-barrier very poorly, although very small amounts (< 1%) do appear to enter

2223-475: The body, including: Blood accounts for 7% of the human body weight, with an average density around 1060 kg/m , very close to pure water's density of 1000 kg/m . The average adult has a blood volume of roughly 5 litres (11 US pt) or 1.3 gallons, which is composed of plasma and formed elements . The formed elements are the two types of blood cell or corpuscle – the red blood cells , (erythrocytes) and white blood cells (leukocytes), and

2280-406: The body. Typically, the biological half-life refers to the body's natural detoxification (cleansing) through liver metabolism and through the excretion of the measured substance through the kidneys and intestines. This concept is used when the rate of removal is roughly exponential . In a medical context, half-life explicitly describes the time it takes for the blood plasma concentration of

2337-399: The brain have been found to be as much as 1000-fold higher than peripheral levels. Half-times apply to processes where the elimination rate is exponential. If C ( t ) {\displaystyle C(t)} is the concentration of a substance at time t {\displaystyle t} , its time dependence is given by where k is the reaction rate constant . Such

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2394-422: The cell fragments called platelets that are involved in clotting. By volume, the red blood cells constitute about 45% of whole blood, the plasma about 54.3%, and white cells about 0.7%. Whole blood (plasma and cells) exhibits non-Newtonian fluid dynamics . One microliter of blood contains: 45 ± 7 (38–52%) for males 42 ± 5 (37–47%) for females Oxygenated: 98–99% Deoxygenated: 75% About 55% of blood

2451-413: The digestive tract. After severe acute blood loss, liquid preparations, generically known as plasma expanders, can be given intravenously, either solutions of salts (NaCl, KCl, CaCl 2 etc.) at physiological concentrations, or colloidal solutions, such as dextrans, human serum albumin , or fresh frozen plasma. In these emergency situations, a plasma expander is a more effective life-saving procedure than

2508-431: The exact color. Arterial blood and capillary blood are bright red, as oxygen imparts a strong red color to the heme group. Deoxygenated blood is a darker shade of red; this is present in veins, and can be seen during blood donation and when venous blood samples are taken. This is because the spectrum of light absorbed by hemoglobin differs between the oxygenated and deoxygenated states. Blood in carbon monoxide poisoning

2565-433: The half-life of the largest component is called the dominant half-life. For a more detailed description see Pharmacokinetics § Multi-compartmental models . Blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells , and transports metabolic waste products away from those same cells. Blood

2622-621: The human body can be prevented by giving an appropriate amount of ethanol to a person who has ingested methanol. Methanol is very toxic and causes blindness and death. A person who has ingested ethylene glycol can be treated in the same way. Half life is also relative to the subjective metabolic rate of the individual in question. Active metabolite ( N-desalkylflurazepam ): 47–100 hours 8–15 hours (higher doses) in rare cases up to 8 days Active metabolite ( nordazepam ): 30–200 hours Active lipophilic metabolite ( norfluoxetine ): 4–16 days The biological half-life of caesium in humans

2679-530: The lungs is still roughly 75% (70 to 78%) saturated. Increased oxygen consumption during sustained exercise reduces the oxygen saturation of venous blood, which can reach less than 15% in a trained athlete; although breathing rate and blood flow increase to compensate, oxygen saturation in arterial blood can drop to 95% or less under these conditions. Oxygen saturation this low is considered dangerous in an individual at rest (for instance, during surgery under anesthesia). Sustained hypoxia (oxygenation less than 90%),

2736-407: The movement of skeletal muscles , which can compress veins and push blood through the valves in veins toward the right atrium . The blood circulation was famously described by William Harvey in 1628. In vertebrates, the various cells of blood are made in the bone marrow in a process called hematopoiesis , which includes erythropoiesis , the production of red blood cells; and myelopoiesis ,

2793-464: The observation of blood clotting in a transparent container. When blood is drawn in a glass container and left undisturbed for about an hour, four different layers can be seen. A dark clot forms at the bottom (the "black bile"). Above the clot is a layer of red blood cells (the "blood"). Above this is a whitish layer of white blood cells (the "phlegm"). The top layer is clear yellow serum (the "yellow bile"). In general, Greek thinkers believed that blood

2850-419: The oxygen is consumed; afterwards, venules and veins carry deoxygenated blood back to the heart. Under normal conditions in adult humans at rest, hemoglobin in blood leaving the lungs is about 98–99% saturated with oxygen , achieving an oxygen delivery between 950 and 1150 ml/min to the body. In a healthy adult at rest, oxygen consumption is approximately 200–250 ml/min, and deoxygenated blood returning to

2907-505: The production of white blood cells and platelets. During childhood, almost every human bone produces red blood cells; as adults, red blood cell production is limited to the larger bones: the bodies of the vertebrae, the breastbone (sternum), the ribcage, the pelvic bones, and the bones of the upper arms and legs. In addition, during childhood, the thymus gland, found in the mediastinum , is an important source of T lymphocytes . The proteinaceous component of blood (including clotting proteins)

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2964-406: The relationship is described by the following equation: In clinical practice, this means that it takes 4 to 5 times the half-life for a drug's serum concentration to reach steady state after regular dosing is started, stopped, or the dose changed. So, for example, digoxin has a half-life (or t ⁠ 1 / 2 ⁠ ) of 24–36 h; this means that a change in the dose will take the best part of

3021-422: The second and the third most supplied organs, with 1100 ml/min and ~700 ml/min, respectively. Relative rates of blood flow per 100 g of tissue are different, with kidney, adrenal gland and thyroid being the first, second and third most supplied tissues, respectively. The restriction of blood flow can also be used in specialized tissues to cause engorgement, resulting in an erection of that tissue; examples are

3078-489: The surface (e.g., during warm weather or strenuous exercise) causes warmer skin, resulting in faster heat loss. In contrast, when the external temperature is low, blood flow to the extremities and surface of the skin is reduced and to prevent heat loss and is circulated to the important organs of the body, preferentially. Rate of blood flow varies greatly between different organs. Liver has the most abundant blood supply with an approximate flow of 1350 ml/min. Kidney and brain are

3135-443: The total blood oxygen capacity seventyfold, compared to if oxygen solely were carried by its solubility of 0.03 ml O 2 per liter blood per mm Hg partial pressure of oxygen (about 100 mm Hg in arteries). With the exception of pulmonary and umbilical arteries and their corresponding veins, arteries carry oxygenated blood away from the heart and deliver it to the body via arterioles and capillaries , where

3192-489: Was discovered in the year 1900 by Karl Landsteiner . Jan Janský is credited with the first classification of blood into the four types (A, B, AB, and O) in 1907, which remains in use today. In 1907 the first blood transfusion was performed that used the ABO system to predict compatibility. The first non-direct transfusion was performed on 27 March 1914. The Rhesus factor was discovered in 1937. Due to its importance to life, blood

3249-464: Was made from food. Plato and Aristotle are two important sources of evidence for this view, but it dates back to Homer's Iliad . Plato thinks that fire in our bellies transform food into blood. Plato believes that the movements of air in the body as we exhale and inhale carry the fire as it transforms our food into blood. Aristotle believed that food is concocted into blood in the heart and transformed into our body's matter. The ABO blood group system

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