Term Papers on Effects Of Altitude On Human Physiology

Term Paper Title	Effects Of Altitude On Human Physiology
# of Words	3959
# of Pages (250 words per page double spaced)	15.84

Effects Of Altitude On Human Physiology

                     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.

  HIGH ALTITUDE
  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 significantly less. At sea level the barometric
  pressure averages 760 mmHg while at 12,000 feet it is only 483 mmHg. This decrease in total
  atmospheric pressure means that there are 40% fewer oxygen molecules per breath at this altitude
  compared to sea level (Princeton, 1995).

  HUMAN RESPIRATORY SYSTEM
  The human respiratory system is responsible for bringing oxygen into the body and transferring it
  to the cells where it can be utilized for cellular activities. It also removes carbon dioxide from the
  body. The respiratory system draws air initially either through the mouth or nasal passages. Both
  of these passages join behind the hard palate to form the pharynx. At the base of the pharynx are
  two openings. One, the esophagus, leads to the digestive system while the other, the glottis, leads
  to the lungs. The epiglottis covers the glottis when swallowing so that food does not enter the
  lungs. When the epiglottis is not covering the opening to the lungs air may pass freely into and out
  of the trachea.

  The trachea sometimes called the "windpipe" branches into two bronchi which in turn lead to a
  lung. Once in the lung the bronchi branch many times into smaller bronchioles which eventually
  terminate in small sacs called alveoli. It is in the alveoli that the actual transfer of oxygen to the
  blood takes place.

  The alveoli are shaped like inflated sacs and exchange gas through a membrane. The passage of
  oxygen into the blood and carbon dioxide out of the blood is dependent on three major factors:
  1) the partial pressure of the gases, 2) the area of the pulmonary surface, and 3) the thickness of
  the membrane (Gerking, 1969). The membranes in the alveoli provide a large surface area for the
  free exchange of gases. The typical thickness of the pulmonary membrane is less than the
  thickness of a red blood cell. The pulmonary surface and the thickness of the alveolar membranes
  are not directly affected by a change in altitude. The partial pressure of oxygen, however, is ...

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