Aerospace physiology is the study of the effects of high altitudes on the body, such as different pressures and levels of oxygen.
[1] Aviation physiology can also include the effect in humans and animals exposed for long periods of time inside pressurized cabins.
[2] The other main issue with altitude is hypoxia, caused by both the lack of barometric pressure and the decrease in oxygen as the body rises.
With a person acclimated to sea level, ventilation increases about five times and the carbon dioxide partial pressure decreases up to 6 mmHg.
These effects will affect a non-acclimated person starting in an altitude of 3650 meters above sea level.
Pulmonary arterial pressure will increase even if the person is acclimated, presenting dilatation of the right side of the heart.
Peripheral arterial pressure is decreased, leading to congestive cardiac insufficiency, and death if exposure is long enough.
[3] A person that stays for a period of time at higher altitudes acclimates, producing fewer effects over the human body.
[11] Arterial chemical receptors are stimulated by exposure to a low partial pressure and hence increase alveolar ventilation, up to a maximum of 1.65 times.
Almost immediately, compensation for the higher altitude begins with an increase of pulmonary ventilation eliminating a large amount CO2.
[13] The kidneys respond to low carbon dioxide partial pressure by decreasing the secretion of hydrogen ions, and increasing the excretion of bicarbonate.
The respiratory center responds to the stimulation of the peripheral chemical receptors produced by the hypoxia after the kidneys have recover the alkalosis.