on higher mountains difficulty in breathing is due to partia pressure of oxygen ,can u pls explain how?

When you travel to a place above about 8,000 feet, your body starts telling you there’s something seriously wrong with the air up there. The “thin” air at high altitudes has considerably less oxygen and pressure. This is because the earth’s gravity holds the oxygen close to the surface — so much so thathalfof the oxygen in the atmosphere is found below 18,000 feet. For comparison, Mount Everest is about 29,000 feet.

With so much less oxygen, your body has to breathe more to get the same amount of oxygen. This leads to the shortness of breath, dizziness and tiredness indicative of altitude sickness.

In order for your lungs to breathe air in without difficulty, the pressure has to be higher outside your body. But at high altitudes, the outside air pressure is lower than it is inside your lungs, making it more difficult to pull in the thinner air and for your veins to pump oxygen throughout the body. As a result, heart rate and blood pressure rises high. This can lead to more unpleasant symptoms, including headache and confusion.