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The effects of high altitude on humans are mostly the consequences of reduced partial pressure of oxygen in the atmosphere. The medical problems that are direct consequence of high altitude are caused by the low inspired partial pressure of oxygen, which is caused by the reduced atmospheric pressure, and the constant gas fraction of oxygen in ...
A person that stays for a period of time at higher altitudes acclimates, producing fewer effects over the human body. [3] There are several mechanisms that help with acclimation, which are an increase of pulmonary ventilation, higher erythrocytes levels, increase of the pulmonary diffusion capacity and increase of the vascularization of the ...
High-altitude adaptation in humans is an instance of evolutionary modification in certain human populations, including those of Tibet in Asia, the Andes of the Americas, and Ethiopia in Africa, who have acquired the ability to survive at altitudes above 2,500 meters (8,200 ft). [1]
The adaptations of Tibetans to their hypoxic ventilatory response interact with other adaptations to promote successful reproduction. For example, Tibetans have evolved a greater oxygen saturation during infancy, leading to a lower rate of child mortality than experienced by non-adapted populations at altitude. [35]
Altitude sickness, the mildest form being acute mountain sickness (AMS), is a harmful effect of high altitude, caused by rapid exposure to low amounts of oxygen at high elevation. [ 1 ] [ 2 ] [ 3 ] People's bodies can respond to high altitude in different ways.
High-altitude cerebral edema (HACE) is a medical condition in which the brain swells with fluid because of the physiological effects of traveling to a high altitude. It generally appears in patients who have acute mountain sickness and involves disorientation, lethargy, and nausea among other symptoms.
Many deaths in high-altitude mountaineering have been caused by the effects of the death zone, either directly by the loss of vital functions or indirectly by poor decisions made under stress (e.g., not turning back in deteriorating conditions, or misreading the climbing route), or physical weakening leading to accidents (e.g., falls).
The adaptation of humans to high altitude is an example of natural selection in action. [2] High-altitude adaptations provide examples of convergent evolution, with adaptations occurring simultaneously on three continents. Tibetan humans and Tibetan domestic dogs share a genetic mutation in EPAS1, but it has not been seen in Andean humans. [3]