Question

When a person who lives at sea level travels to a high altitude, they are moving to an area with a lower atmospheric pressure. The number of oxygen molecules in a breath is the same, but there is lower partial pressure of oxygen; thus the lower air pressure results in less diffusion of oxygen into the blood for each breath compared to a breath at sea level. How would this change in oxygen availability affect the person’s heart rate and breathing rate? Why?

Answer 1

ANSWER (Intro, how) The air at higher altitudes contains fewer oxygen molecules. This means that you need to take more breaths in order to get the same amount of oxygen as you would at lower altitudes. The higher the alitude,the higher is the difficulty level in breathing.

ANSWER (Detailed How) At, elevated altitudes, the change in oxygen availability can affect the person’s heart rate and breathing rate in numerous ways. There arises increase iin systolic blood pressure and decrease in arterial oxygen saturation.

When moving at higher altitudes, acclimatization starts to occur and resting heart rate starts to decrease back to the sea level value reaching it after several days to two weeks at a certain altitude. At around 2000m, heart rate will be about 10% above the sea level value. Acclimatization is the body's natural way of defending altitude sickness and adapting to the decrease in oxygen concentration at a specific altitude.

ANSWER (Why) At high altitude, in the short term, the lack of oxygen is sensed by the peripheral chemoreceptors, which causes an increase in ventilation.

During acclimatization, a number of changes must take place for the body to operate with decreased oxygen.

(1) increasing the depth of respiration;

(2) the body manufactures more red blood cells to counteract the lower oxygen saturation in blood in high altitudes;

(3) forcing blood into portions of the lung that are normally not used at sea level;

(4) increasing the pressure in the pulmonary arteries; etc.