H.6.7+Explain+the+problem+of+gas+exchange+at+high+altitudes+and+the+way++the+body+acclimatizes

//-// At high altitudes, atmospheric pressure is less, therefore the partial pressure (pO2) is less - As partial pressure of oxygen decreases, the percentage saturation of hemoglobin decreases rapidly as well; hence, hemoglobin is not fully saturated as it passes through the lungs and the tissues of the body are supplied with less oxygen. - This is because hemoglobin has a low affinity for oxygen at low partial pressures as shown by the oxygen dissociation curve



Disorders caused by high altitudes: - Mountain sickness may occur when a person travels quickly from a low to high altitude - Symptoms include mild headaches, dizziness and nausea - these symptoms wear off as one becomes //acclimatised// - Fatal disorders can include fluid build up in the lungs and swelling of the brain

The Body's Adjustment: - The higher the altitude, the longer the adjustment - Immediately, the heart pumps faster - After several days, some blood vessels increase in diameter - After a few weeks the rate and depth of breathing increase to bring more air into the lungs (ventilation rate increases), you develop more capillaries, and extra red blood cells are produced, increasing the hemoglobin content in the blood and the amount of oxygen the blood can carry. -Muscles produce more myoglobin (=protein used to store oxygen in muscles).

Those who live at higher altitudes have more hemoglobin, more myoglobin (about 25% greater of body content), more capillaries, hyperventilation (tidal volume is greater), increased lung surface area, larger and more numerous mitochondria.

Myoglobin vs. Hemoglobin - Myoglobin has an oxygen dissociation curve to the left of hemoglobin's - Myoglobin remains fuly saturated with oxygen at partial pressures lower than that required for hemoglobin to give up its oxygen - Myoglobin stores oxygen, releasing it when partial pressure is very low, as in severe muscular exertion