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Encyclopedia > Ischemia

In medicine, ischemia (Greek ισχαιμία, isch- is restriction, hema or haema is blood) is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. Also, several fraternities, including Sigma Beta Rho, have adopted it for brothers names, including Neil Tembulkar in the Georgia Tech Chapter. It may also be spelled ischaemia or ischæmia. Image File history File links Question_book-3. ... For the chemical substances known as medicines, see medication. ... For other uses, see Blood (disambiguation). ... f you all The blood vessels are part of the circulatory system and function to transport blood throughout the body. ...

Contents

Mechanism

Rather than in hypoxia, a more general term denoting a shortage of oxygen (usually a result of lack of oxygen in the air being breathed), ischemia is an absolute or relative shortage of the blood supply to an organ. Relative shortage means the mismatch of blood supply (oxygen delivery) and blood request for adequate oxygenation of tissue. Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ...


Ischemia can also be described as an inadequate flow of blood to a part of the body, caused by constriction or blockage of the blood vessels supplying it. Ischemia of heart muscle produces angina pectoris.


This can be due to:

This article or section does not cite any references or sources. ... The heart and lungs, from an older edition of Grays Anatomy. ... Section of an artery For other uses, see Artery (disambiguation). ... In physiology and medicine, hypotension refers to an abnormally low blood pressure. ... Septic shock is a very serious medical condition caused by decreased tissue perfusion and oxygen delivery as a result of infection and sepsis. ... Thrombosis is the formation of a clot or thrombus inside a blood vessel, obstructing the flow of blood through the circulatory system. ... For malignant tumors specifically, see cancer. ... The amniotic sac is a tough but thin transparent pair of membranes which holds a developing embryo (and later fetus) until shortly before birth. ... Amniotic fluid embolism (AFE) is a rare and incompletely understood obstetric emergency in which amniotic fluid, fetal cells, hair or other debris enters the mothers blood stream via the placental bed of the uterus and triggers an allergic reaction. ... ... The term g force or gee force refers to the symbol g, the force of acceleration due to gravity at the earths surface. ...

Consequences

Since oxygen is mainly bound to hemoglobin in red blood cells, insufficient blood supply causes tissue to become hypoxic, or, if no oxygen is supplied at all, anoxic. This can cause necrosis (i.e. cell death). In very aerobic tissues such as heart and brain, at body temperature necrosis due to ischemia usually takes about 3-4 hours before becoming irreversible. This and typically some collateral circulation to the ischemic area accounts for the efficacy of "clot-buster" drugs such as Alteplase, given for stroke and heart-attack within this time period. However, complete cessation of oxygenation of such organs for more than 20 minutes typically results in irreversible damage. Structure of hemoglobin. ... “Red cell” redirects here. ... Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ... Necrosis (in Greek Νεκρός = Dead) is the name given to accidental death of cells and living tissue. ... Necrosis (in Greek Νεκρός = Dead) is the name given to accidental death of cells and living tissue. ... In blood coagulation, tissue plasminogen activator (tPA) is an enzyme (EC 3. ...


Ischemia is a feature of heart diseases, transient ischemic attacks, cerebrovascular accidents, ruptured arteriovenous malformations, and peripheral artery occlusive disease. The heart, the kidneys, and the brain are among the organs that are the most sensitive to inadequate blood supply. Ischemia in brain tissue, for example due to stroke or head injury, causes a process called the ischemic cascade to be unleashed, in which proteolytic enzymes, reactive oxygen species, and other harmful chemicals damage and may ultimately kill brain tissue. Heart disease is an umbrella term for a number of different diseases which affect the heart and as of 2007 it is the leading cause of death in the United States,[1] and England and Wales. ... A transient ischemic attack (TIA, often colloquially referred to as mini stroke) is caused by the temporary disturbance of blood supply to a restricted area of the brain, resulting in brief neurologic dysfunction that usually persists for less than 24 hours. ... For other uses, see Stroke (disambiguation). ... Arteriovenous malformation or AVM is a congenital disorder of the veins and arteries that make up the vascular system . ... In medicine, peripheral artery occlusive disease (PAOD), also known as peripheral vascular disease (PVD) and peripheral artery disease (PAD) is a collator for all diseases caused by the obstruction of large peripheral arteries, which can result from atherosclerosis, inflammatory processes leading to stenosis, an embolism or thrombus formation. ... The heart and lungs, from an older edition of Grays Anatomy. ... The kidneys are the organs that filter wastes (such as urea) from the blood and excrete them, along with water, as urine. ... For other uses, see Brain (disambiguation). ... A stroke or cerebrovascular accident (CVA) occurs when the blood supply to a part of the brain is suddenly interrupted by occlusion (an ischemic stroke- approximately 90% of strokes), by hemorrhage (a hemorrhagic stroke - less than 10% of strokes) or other causes. ... Traumatic brain injury (TBI), traumatic injuries to the brain, also called intracranial injury, or simply head injury, occurs when a sudden trauma causes brain damage. ... The ischemic cascade is a series of biochemical reactions that take place in the brain after seconds to minutes of ischemia (inadequate blood supply) (Arnold, 2003). ... Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion. ... Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = blend) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ... Reactive oxygen species (ROS) include oxygen ions, free radicals and peroxides both inorganic and organic. ...


Restoration of blood flow after a period of ischemia can actually be more damaging than the ischemia. Reintroduction of oxygen causes a greater production of damaging free radicals, resulting in reperfusion injury. With reperfusion injury, necrosis can be greatly accelerated. In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ... Reperfusion injury refers to damage to tissue caused when blood supply returns to the tissue after a period of ischemia. ...


Variations

The mechanism of ischemia depends on the type. One important type is cardiac ischemia, another is bowel ischemia.


Cardiac ischemia

Cardiac ischemia may cause chest pain, known as angina pectoris


Detection

Initial evaluation of chest-pain patients involves a 12 lead electrocardiogram (ECG) and cardiac markers such as troponins. These tests are highly specific but very insensitive and often leave the requirement for further testing to achieve an accurate diagnosis. Magnetocardiography (MCG) imaging utilises superconducting quantum interference devices (SQUIDs) to detect the weak magnetic fields generated by the heart's electrical fields. There is a direct correlation between abnormal cardiac depolarisation or repolarisation and abnormality in the magnetic field map. In July 2004, the Food and Drug Administration (FDA) approved the CardioMag Imaging MCG as a safe device for the non-invasive detection of ischemia. “QRS” redirects here. ... Troponin Troponin is a complex of three proteins that is integral to muscle contraction in skeletal and cardiac muscle, but not smooth muscle. ... Magnetocardiography (MCG) is a technique to measure the magnetic fields produced by electrical activity in the heart using extremely sensitive devices such as the Superconducting Quantum Interference Device (SQUIDs(. If the magnetic field is measured using a multichannel device, a map of the magnetic field is obtained over the chest... “FDA” redirects here. ...


Bowel ischemia

An ischemia in the large bowel caused by an inflammation results in ischemic colitis. An ischemia in the small bowel, on the other hand, caused by an inflammation results in mesenteric ischemia. Ischemic colitis is inflammation of the intestine (colitis) caused by inadequate blood supply (ischemia) to meet the metabolic demands. ... This page may meet Wikipedias criteria for speedy deletion. ...


Cutaneous ischemia

Reduced blood flow to the skin layers may result in mottling or uneven, patchy discoloration of the skin.


Treatment

A dietary supplement based on superoxide dismutase and wheat gliadin (also known as glisodin) has shown promise in the protection against ischemia-reperfusion injury by inhibiting oxidative DNA damage. A dietary supplement is intended to supply nutrients, (vitamins, minerals, fatty acids or amino acids) that are missing or not consumed in sufficient quantity in a persons diet. ... Structure of the monomeric unit of human superoxide dismutase 2 The enzyme superoxide dismutase (SOD, EC 1. ... Gliadin is a glycoprotein, present in wheat and some other cereals, best known for its role, along with glutenin, in the formation of gluten. ... Reperfusion injury refers to damage to tissue caused when blood supply returns to the tissue after a period of ischemia. ...


References

Notes

  • Oxford Reference: Concise Medical Dictionary (1990, 3rd ed.). Oxford University Press: Market House Books.

See also

Cerebral ischemia is an ischemic condition where the brain or parts of the brain do not receive enough blood flow to maintain normal neurological function. ... This article does not adequately cite its references or sources. ... The ischemic cascade is a series of biochemical reactions that take place in the brain after seconds to minutes of ischemia (inadequate blood supply) (Arnold, 2003). ... Reperfusion injury refers to damage to tissue caused when blood supply returns to the tissue after a period of ischemia. ... A renal cell carcinoma (chromophobe type) viewed on a hematoxylin & eosin stained slide Pathologist redirects here. ... This article is about the medical term. ... Necrosis (in Greek Νεκρός = Dead) is the name given to accidental death of cells and living tissue. ... An infection is the detrimental colonization of a host organism by a foreign species. ... An abscess on the skin, showing the redness and swelling characteristic of inflammation. ... Wound healing, or wound repair, is the bodys natural process of regenerating dermal and epidermal tissue. ... Neoplasia (new growth in Greek) is abnormal proliferation of cells in a tissue or organ. ... Anatomic pathology is a medical specialty (a branch of pathology) that is concerned with the diagnosis of disease based on the gross, microscopic, and molecular examination of cells and tissues. ... Anatomic pathology is a medical specialty (a branch of pathology) that is concerned with the diagnosis of disease based on the gross, microscopic, and molecular examination of cells and tissues. ... Cytopathology is a branch of pathology that studies and diagnoses diseases on the cellular level. ... This article is about the medical procedure. ... Molecular pathology is an emerging discipline within anatomic pathology which is focused on the use of nucleic acid-based techniques such as DNA sequencing, fluorescent in-situ hybridization, reverse-transcriptase polymerase chain reaction, and nucleic acid microarrays for specialised studies of disease in tissues and cells. ... Forensic pathology is a branch of medicine concerned with determining cause of death, usually for criminal law cases and civil law cases in some jurisdictions. ... Dental pathologists are doctors of dental science who specialise in the diagnosis and characterization of diseases of the teeth, jaw, and maxilla through the examination of tissue specimens. ... Gross examination or grossing is the process by which pathology specimens are inspected with the naked eye to obtain diagnostic information, while being processed for further microscopic examination. ... Histopathology is a field of pathology which specialises in the histologic study of diseased tissue. ... Immunohistochemistry or IHC refers to the process of localizing proteins in cells of a tissue section exploiting the principle of antibodies binding specifically to antigens in biological tissues. ... The electron microscope is a microscope that can magnify very small details with high resolving power due to the use of electrons rather than light to scatter off material, magnifying at levels up to 500,000 times. ... Immunofluorescence is the labeling of antibodies or antigens with fluorescent dyes. ... A metaphase cell positive for the bcr/abl rearrangement using FISH. The chromosomes can be seen in blue. ... Clinical Pathology is one of the two major divisions of Pathology. ... Clinical chemistry (also known as clinical biochemistry, chemical pathology or pure blood chemistry) is the area of pathology that is generally concerned with analysis of bodily fluids. ... Hematopathology is the branch of pathology which studies diseases of hematopoietic cells (see below). ... Transfusion medicine (or transfusiology) is the branch of medicine that is concerned with the transfusion of blood and blood components. ... Medical microbiology is a branch of microbiology which deals with the study of microorganisms including bacteria, viruses, fungi and parasites which are of medical importance and are capable of causing diseases in human beings. ... The specificity of the bond between antibody and antigen has made it an excellent tool in the detection of substances in a variety of diagnostic techniques, known collectively as diagnostic immunology. ... Enzyme assays are laboratory methods for measuring enzymatic activity. ... Mass spectrometry (previously called mass spectroscopy (deprecated) or informally, mass-spec and MS) is an analytical technique that measures the mass-to-charge ratio of ions. ... For the Second Person album, see Chromatography (album). ... Analysis of a marine sample of photosynthetic picoplankton by flow cytometry showing three different populations (Prochlorococcus, Synechococcus and picoeukaryotes) Flow cytometry is a technique for counting, examining and sorting microscopic particles suspended in a stream of fluid. ... A blood bank is a cache or bank of blood or blood components, gathered as a result of blood donation, stored and preserved for later use in blood transfusions. ... A microbiological culture is a way to determine the cause of infectious disease by letting the agent multiply (reproduce) in predetermined media. ... Serology is the scientific study of blood serum. ...

  Results from FactBites:
 
Silent Ischemia - Texas Heart Institute Heart Information Center (570 words)
Ischemia is a condition where the flow of oxygen-rich blood to a part of the body is restricted.
Cardiac ischemia refers to lack of blood flow and oxygen to the heart muscle.
If ischemia is severe or lasts too long, it can cause a heart attack (myocardial infarction) and can lead to heart tissue death.
INTESTINAL ISCHEMIA - Patients - American College of Gastroenterology (2419 words)
Intestinal ischemia is the term used to describe the result of a variety of disorders all of which ultimately reflect a state of insufficient blood flow to the small intestine, the colon, or both -- collectively referred to as the intestines.
The injury and prognosis for any given episode of intestinal ischemia depend on the cause of the injury, the blood vessel(s) involved, the underlying medical condition of the patient, and the swiftness with which the problem is brought to medical attention for diagnosis and treatment.
The most common cause of ischemia from venous obstruction is a thrombus which, as it interferes with return of blood flow from the intestines, produces intestinal congestion, and resulting intestinal swelling and thickening, as well as bleeding.
  More results at FactBites »

 
 

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