When you travel to high altitudes, the air pressure is lower, meaning fewer oxygen molecules are present in the air. Kenneth Baillie, a clinical lecturer in anesthesia and intensive care medicine at the University of Edinburgh, reports for every 1,000 feet that you ascend in elevation, a loss of about 3 percent of oxygen occurs. High altitude is defined at starting at 8,000 feet, where there are about 25 percent fewer oxygen molecules available per breath. The drop in oxygen levels can have a negative effect on the body and the body must find ways to compensate for the lack of oxygen.
Vital Signs Increase
Both heart rate and respiratory rate increases as altitude increases. Respiratory rate is how many breaths an individual takes per minute. During initial exposure to altitude the body must increase respiratory rate in order to get more oxygen to the body and expel carbon dioxide. Heart rate increases as respiratory rate increases to help pump oxygen through the body.
Red Blood Cells
One way the body acclimatizes to high altitude is by increasing the amount of red blood cells produced. It takes the body about four to five days to create new red blood cells and after an individual has been exposed to altitude for long periods of time, they will have 30 percent to 50 percent more red blood cells than an individual at sea level, according to Rick Curtis, director of the Outdoor Action Program at Princeton University. The body also creates more capillaries to match the production of new red blood cells. Extra capillaries decrease the distance between the cell and capillary, making it easier to transport oxygen throughout the body.
Low humidity, dry air and increased respiratory rate are all factors that contribute to dehydration at high altitude. Above 6,000 feet, the body exhales and perspires twice as much moisture than at sea level. Also as a result of lower air pressure moisture from the skin is evaporated at faster rates that can cause dehydration. With lower levels of oxygen available and less body moisture, the body is more sensitive to diuretics, such as alcohol and caffeine at high altitudes.
The body knows it needs to sustain vital organs with oxygen and because the amount of oxygen available decreases at higher altitudes, the body redistributes blood throughout the body. It decreases the amount of blood flowing to digestive organs and increases blood to the brain, heart and lungs. As a result of more blood being pumped through the arteries to the brain, headaches are common. Lack of blood flow to the digestive organs can cause nausea, vomiting and loss of appetite.