THE EFFECTS OF ALTITUDE ON HUMAN PHYSIOLOGY
Changes in altitude have a profound effect on the human body. The body
attempts to maintain a state of homeostasis or balance to ensure the optimal
operating environment for its complex chemical systems. Any change from this
homeostasis is a change away from the optimal operating environment. The body
attempts to correct this imbalance. One such imbalance is the effect of
increasing altitude on the body's ability to provide adequate oxygen to be
utilized in cellular respiration. With an increase in elevation, a typical
occurrence when climbing mountains, the body is forced to respond in various
ways to the changes in external
environment. Foremost of these changes is the diminished ability to obtain
oxygen from the atmosphere. If the adaptive responses to this stressor are
inadequate the performance of body systems may decline dramatically. If
prolonged the results can be serious or even fatal.
In looking at the effect
of altitude on body functioning we first must understand what occurs in the
external environment at higher elevations and then observe the important
changes that occur in the internal environment of the body in response.
In discussing altitude change and its effect on the body mountaineers
generally define altitude according to the scale of high (8,000 - 12,000
feet), very high (12,000 - 18,000 feet), and extremely high (18,000+ feet),
(Hubble, 1995). A common misperception of the change in external environment
with increased altitude is that there is decreased oxygen. This is not
correct as the concentration of oxygen at sea level is about 21% and stays
relatively unchanged until over 50,000 feet (Johnson, 1988).
What is really happening is that the atmospheric pressure is decreasing and
subsequently the amount of oxygen available in a single breath of air is...