The brain, which takes up only 3 percent of total body weight, uses 20 percent of the oxygen. Not surprisingly, the brain is likely to suffer when the supply is short. The third and best-known adjustment to altitude is an increase in the number of red blood cells produced by the bone marrow, thus increasing the amount of oxygen blood can carry. Many other more subtle changes occur if enough time is allowed for acclimatization. Even with acclimatization high on Everest the climber faces other problems.
Sleep is restless and broken with nightmares.
Appetite disappears and climbers must force themselves to take enough calories to meet the needs of work and heat production. Frostbite and hypothermia lurk around the corner, and the exhausted climber who sits down too long to rest may not wake from the fatal sleep of hypothermia. There, exhaustion, hunger, thirst, lack of sleep, cold, even fear, all stretch the human body to its very limit. Museum of Science, Boston Denver Museum of Natural History Fort Worth Museum of Science and History Houston Museum of Natural Science National Museum of Natural Science, Taiwan Science World British Columbia, Vancouver IMAX is a registered trademark of Imax Corporation. All rights reserved.