A deficiency of oxygen, most frequently occurring when blood supply to any part of the body is completely cut off.
Generally, lack of sufficient oxygen in the blood.
Below-normal oxygen in body tissues.
Lack of oxygen in blood or tissues; it may be local due to inadequate oxygen delivery to a localized area or may be global (whole body).
All cellular functions in the body including the neuronal cells in the brain are dependent on adequate oxygenation. A healthy human brain utilizes 20% of total oxygen in¬ haled. Brain cells have a low threshold for oxygen deprivation, because they are unable to respire anaerobically or store oxygen for later use. If the cerebral blood flow drops to 20% of its normal rate, consciousness will be lost within 10 s, followed by interruption of nerve cell metabolism within 30 s, and manifestation of electrophysiological abnormalities within 60 s. Although immediate and adequate perfusion of the brain with oxygen will restore its normal functions, anoxic-hypoxic conditions persisting longer than 4-8 min can result in diffuse neuronal cell death.
Deficiency in or cut-off of oxygen supply to the body, as may happen during pregnancy, in difficult labor, or in some cases of high fever and accidents such as near-drowning. It can also result from anemia in which the blood is unable to carry oxygen to body tissues or from internal toxic conditions in which the tissues are unable to absorb oxygen from the blood. However it occurs, anoxia can cause damage to affected tissues; the brain is especially susceptible, and oxygen starvation has been implicated in numerous developmental disorders, such as learning disabilities.
Absence or abnormally low amount of oxygen in die body; can occur in certain abnormal states (e.g., cardiac arrest, anemia, heart failure, impaired respiration) and at high altitudes.
An abnormal condition caused by a lack of oxygen. There are various types of anoxia, which can be local or system-wide. In anemic anoxia, the person’s blood is unable to carry oxygen to tissues. In cerebral anoxia, circulatory failure causes a life-threatening lack of oxygen in the brain.
A condition in which the tissues of the body receive inadequate amounts of oxygen. This may result from low atmospheric pressure at high altitudes; a shortage of circulating blood, red blood cells, or hemoglobin; or disordered blood flow, such as occurs in heart failure. It can also result from insufficient oxygen reaching the blood in the lungs due to poor breathing movements or because disease, such as pneumonia, is reducing the effective surface area of lung tissue.
That state in which the body tissues have an inadequate supply of oxygen. This may be because the blood in the lungs does not receive enough oxygen; because there is not enough blood to receive the oxygen; or because the blood stagnates in the body.
Absence of oxygen. This term is often used incorrectly to indicate hypoxia.
Anoxia refers to the complete absence of oxygen in a particular body tissue, such as the brain or a muscle. This condition leads to the disturbance of cellular metabolism, or chemical activity, and ultimately culminates in cell death unless timely correction is achieved within a few minutes.
Anoxia is a rare condition that typically arises during instances of cardiopulmonary arrest or asphyxiation. If left uncorrected, anoxia can result in permanent organ damage or even death. In contrast, hypoxia, which refers to the reduction of oxygen supply to a tissue, is a more prevalent issue.