Hypoxia is a condition in which cells of the body are deprived of oxygen. The reasons for this condition can vary within the body. However, the result is that tissues cannot survive for long without oxygen. Continued oxygen deprivation can eventually become fatal.
Cells get their energy from oxygen and glucose. Most cells can survive for a short period using an anaerobic metabolic (energy without oxygen) process. Unfortunately, brain cells cannot. The damage to brain cells when hypoxia occurs is immediate. The blood carries a limited amount of reserve oxygen and brain cell death can occur within minutes of falling below normal oxygen levels. This deprivation can lead to impairment of several functions as the brain cannot work as well and its control over all bodily processes fades. The consumption of alcohol can produce hypoxia, and is one of the reasons why brain functions are impaired when excess alcohol is consumed. Jet pilots are trained about the effects of hypoxia since they are often performing at altitudes where oxygen is scarce. If something should happen to their onboard oxygen supply, they are trained to help cope with some of the effects of hypoxia.
There are several types of hypoxia as well as causes of this dangerous condition. One of the more common types is hypoxic hypoxia. It is the reduction of the amount of oxygen passing into the blood because of a reduced oxygen exchange (i.e., reduced lung capacity) or high altitudes. Reduction in lung capacity may be a result of lung damage, disease or removal of portions of the lungs. Smokers are particularly susceptible to hypoxic hypoxia. People who change altitudes can adjust to the lower oxygen pressure as the blood produces more red blood cells carrying additional hemoglobin (the oxygen-carrying molecule in red blood cells).
Hypemic hypoxia occurs when the number of hemoglobin molecules or red blood cells is reduced. Either condition causes a reduction in the oxygen carrying capacity of the blood to be lowered. The causes of this type of hypoxia can be through hemorrhage or anemia. It can also be caused by drugs, chemicals, or an increase in carbon monoxide (a condition experienced by smokers).
Stagnant hypoxia occurs as a result of poor circulation of the blood. Blood flow is reduced by prolonged sitting in one position, cold temperatures, or being exposed to "g" forces. People who sit in a chair for hours or are sedentary may experience this type of hypoxia. It is important for the elderly or those whose movement is restricted to be sure they get enough oxygen to avoid this type of hypoxia.
Histotic hypoxia is the inability of the tissues to use oxygen. When organ tissues are involved, they appear blue in color and are called cyanotic. Drinking alcoholic beverages, poisoning by cyanide or carbon monoxide, and certain narcotics can impair gaseous exchange in the tissues, and lead to hypoxia.
The blue color associated with cyanosis, especially noted around the lips, is due to the build-up of high levels of deoxygenated hemoglobin in capillaries. Prolonged hypoxia can lead to tissue death or impairment.
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