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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. Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells such as nutrients and oxygen—and transports Waste products The blood vessels are part of the Circulatory system and function to transport Blood throughout the body It may also be spelled ischaemia or ischæmia.

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. Chronic Hypoxia is a pathological condition in which the body as a whole ( generalized hypoxia) or region of the body ( tissue hypoxia) is deprived of adequate Relative shortage means the mismatch of blood supply (oxygen delivery) and blood request for adequate oxygenation of tissue. Ischemia results in tissue damage because of a lack of oxygen and nutrients. Ultimately, this causes great damage because of a buildup of metabolic wastes.

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. Angina pectoris, commonly known as angina, is severe Chest pain due to Ischemia (a lack of blood and hence Oxygen supply of the heart

This can be due to:

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. Amniotic fluid embolism (AFE is a rare and incompletely understood Obstetric emergency in which Amniotic fluid, fetal cells hair or other debris enters Sickle-cell disease or sickle-cell anaemia (or anemia) is a Blood disorder characterized by Red blood cells that assume an abnormal rigid g-force (also G-force, g-load) is a measurement of an object's Acceleration expressed in g s Hemoglobin ( also spelled haemoglobin and abbreviated Hb or Hgb) is the Iron -containing Oxygen -transport Metalloprotein Red blood cells are the most common type of Blood cell and the Vertebrate body's principal means of delivering Oxygen to the body tissues via the Blood Chronic Hypoxia is a pathological condition in which the body as a whole ( generalized hypoxia) or region of the body ( tissue hypoxia) is deprived of adequate This can cause necrosis (i. Necrosis (in Greek Νεκρός = "dead" is the name given to unnatural Death of cells and living tissue. 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. Necrosis (in Greek Νεκρός = "dead" is the name given to unnatural Death of cells and living tissue. 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. Tissue plasminogen activator (abbreviated tPA or PLAT) is a Protein involved in the breakdown of Blood clots Specifically it is a However, complete cessation of oxygenation of such organs for more than 20 minutes typically results in irreversible damage.

Ischemia is a feature of heart diseases, transient ischemic attacks, cerebrovascular accidents, ruptured arteriovenous malformations, and peripheral artery occlusive disease. Heart disease is an Umbrella term for a variety for different diseases affecting the Heart. A transient ischemic attack ( TIA, often colloquially referred to as “ mini stroke ” is caused by the changes in the blood supply to a particular area of the A stroke is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain Cerebral arteriovenous malformation Arteriovenous malformation or AVM in the majority of cases is a Congenital disorder consisting of a connection between Peripheral vascular disease (PVD also known as peripheral artery disease (PAD or peripheral artery occlusive disease (PAOD is a collator for all Diseases The heart, the kidneys, and the brain are among the organs that are the most sensitive to inadequate blood supply. The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic The kidneys are complicated organs that have numerous biological roles The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain 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. A stroke is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain Traumatic brain injury (TBI also called intracranial injury, occurs when Physical trauma injures the Brain. The ischemic (ischaemic cascade is a series of biochemical reactions that take place in the Brain and other aerobic tissues after seconds to minutes of Ischemia (inadequate Proteolysis is the directed degradation ( digestion) of Proteins by cellular Enzymes called Proteases or by intramolecular digestion Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Reactive oxygen species (ROS are ions or very small molecules that include Oxygen Ions free radicals, and Peroxides both inorganic and

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. In Chemistry, radicals (often referred to as free radicals) are atoms molecules or ions with Unpaired electrons on an otherwise Open shell Reperfusion injury refers to damage to tissue caused when Blood supply returns to the tissue after a period of Ischemia. With reperfusion injury, necrosis can be greatly accelerated.

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. Angina pectoris, commonly known as angina, is severe Chest pain due to Ischemia (a lack of blood and hence Oxygen supply of the heart Troponin is a complex of three regulatory proteins that is integral to Muscle contraction in skeletal and Cardiac muscle, but not Smooth muscle 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. 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 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.

Bowel ischemia

An ischemia in the large bowel caused by an inflammation results in ischemic colitis. This article concerns ischemia of the large bowel See Mesenteric ischemia for ischemia of small bowel Ischemic colitis (Ischaemic Colitis An ischemia in the small bowel, on the other hand, caused by an inflammation results in mesenteric ischemia. This article concerns ischemia of the small bowel See Ischemic colitis for ischemia of the large bowel Mesenteric ischemia (Mesenteric

Cutaneous ischemia

Reduced blood flow to the skin layers may result in mottling or uneven, patchy discoloration of the skin. Mottle or mottling is the appearance of uneven usually yellowish spots on Plants It is usually a symptom of disease or malnutrition

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. The enzyme superoxide dismutase ( SOD,) catalyzes the Dismutation of Superoxide into Oxygen and Hydrogen peroxide. Gliadin is a Glycoprotein present in Wheat and several other Cereals within the grass genus Triticum. Glisodin is a Nutritional supplement based on two constituents Cantaloupe extract which typically contains high quantities of the Enzyme Reperfusion injury refers to damage to tissue caused when Blood supply returns to the tissue after a period of Ischemia.

References

Notes

See also

Brain ischemia (or cerebral ischemia) is an Ischemic condition where the Brain or parts of the brain do not receive enough Blood flow to maintain In Medicine, an infarction is the process resulting in a Macroscopic area of necrotic tissue in some organ caused by loss of adequate Blood supply The ischemic (ischaemic cascade is a series of biochemical reactions that take place in the Brain and other aerobic tissues after seconds to minutes of Ischemia (inadequate Reperfusion injury refers to damage to tissue caused when Blood supply returns to the tissue after a period of Ischemia.

Dictionary

ischemia

-noun

  1. (pathology) Alternative spelling of ischaemia.
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