Question

Why do mountaineers usually suffer from nose-bleeding at high altitudes?

Answer 1

Hint: At high altitudes typical of a mountain the atmospheric pressure becomes very low that that at sea level. It is essential that the atmospheric pressure and the pressure exerted by the blood in the blood vessels are close in value.

Complete step by step answer:
In the mountains, the level of oxygen in the air is very less and the air is dry. Also, the atmospheric pressure becomes very low at such altitudes. The deficiency of oxygen in the air makes our blood become very thin and dry. This causes it to lose some of its viscosity and attain a more free-flowing nature.
Also, the low atmospheric pressure can counterbalance the high pressure exerted by the blood in our blood vessels. This imbalance of pressure can cause some of the blood vessels in our nose and the surrounding area to burst. When this happens the thin blood oozes out from the burst blood vessels and comes out from the nose.
Hence, mountaineers usually suffer from nose bleeding at high temperatures.

Additional information:
The body tries to prevent this phenomenon by trying to lower the blood pressure in our vessels. This lowered blood pressure along with the lack of oxygen in the blood causes fatigue and in extreme situations can also lead to unconsciousness. This is why people from the plains often fall sick when they go to the mountains. However, the bodies of the people that live in the mountains adapt to this low oxygen state and they do not fall sick.

Note: Students might think that the biting cold in the mountains must have something to do with the bleeding from the nose. However, this is not true as they must remember that humans are warm blooded animals, which means that the temperature of their bodies remains constant over a small range regardless of the temperature of the environment and hence, the blood vessels and the blood inside them still remain warm. The real reason for nose-bleeding experienced by mountaineers is the one stated in the answer.