1–35C

1–35C Explain why some people experience nose bleeding
and some others experience shortness of breath at high elevations.
ANS
1-35CThe atmospheric pressure, which is the externalpressure exerted on the skin, decreases with
increasing elevation. Therefore, the pressure is lower at higher elevations. As a result, the difference
between the blood pressure inthe veins and the air pressure outside increases. Thispressure imbalance may
cause some thin-walled veins such as the ones inthe nose toburst, causing bleeding. The shortness of
breath iscaused bythe lower air densityathigher elevations, and thus lower amountof oxygen per unit
volume.