Why do mountaineers ususally suffer from nose - bleading at high altitudes ?

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

Why do some people suffer from nose bleeding at higher altitudes?

Why do people suffer from altitude sickness after reaching the high altitude regions ? How does their body acclimatized after a couple of days ?

Mountain sickness at high altitude is due to

Why do malaria patients suffer from anaemia?

It is observed that mountaineers carry oxygen at high altitudes. Give reason

The " mountain sickness" in persons climbing to high altitudes with any aid of oxygen cylinders is due to

Assertion : At higher peaks of mountains, people suffer from high altitude sickness (sluggish feeling, breathlessness etc.) due to lesser oxygen intake at each breather Reason : Air at sea level is dense because it is compressed by the mass of the air above it. The atmospheric pressure at higher peaks of mountains is lower causing the air at those heights to be much less dense than at sea level.