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Effects of Altitude Exposure

Several circulatory changes mediated by stimulation of the

carotid body, which causes activation of the sympathetic nervous system, are stimulated by short-term altitude exposure (less than three or four days) (Wahrenberger, 2003). These changes occur within a few minutes of altitude exposure and are related to a transient epinephrine secretion combined with a more sustained secretion of norepinephrine. These cause immediate changes which include an increase in ventilation, increased heart rate, increased cardiac output, and an elevation of blood pressure. There is also an increase in coronary blood flow. The increased ventilating which occurs with high altitude causes hypocapnia and respiratory alkalosis, which can inhibit the ability to hyperventilate and improve oxygenation. The rapid and significant increase in pressure in the pulmonary artery with initial exposure to attitude is most likely caused by hypoxia, which is induced by vasoconstriction. It is a universal finding, and may be important in the development of pulmonary edema.

The cardiovascular effects of high altitude are particularly noticeable during exercise (Wahrenberger, 2003). A study of 12 healthy office workers found that they showed only a minor elevation of resting heart rate at 8856 feet and 12,136 feet, but when asked to perform a Master's double-step exercise their heart rate increased significantly at these altitudes. Similar findings were observed for blood pressure and rate-pressure product. Increasing altitude was also associated with increasing recovery time to pre-exercise blood pressure. However, arterial oxygen level remained virtually unchanged with exercise at sea level, dropped progressively at rest with increasing altitude, and fell dramatically with exercise at altitude. A combined rate-pressure product and reduced arterial oxygen saturation demonstrates the oxygen supply:demand mismatch with exercise at attitude.

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Effects of Altitude Exposure. (1969, December 31). In LotsofEssays.com. Retrieved 04:33, March 29, 2024, from https://www.lotsofessays.com/viewpaper/1704406.html