What is the impact of high altitude on gas exchange?

High altitude impacts gas exchange by reducing the partial pressure of oxygen, making breathing more difficult.

At high altitudes, the atmospheric pressure is lower than at sea level. This means that the partial pressure of oxygen, which is the pressure that oxygen exerts in a mixture of gases, is also lower. The partial pressure of a gas is directly proportional to its concentration, so at high altitudes, the concentration of oxygen in the air is lower. This makes it more difficult for the body to obtain the oxygen it needs through the process of gas exchange.

Gas exchange occurs in the lungs, where oxygen is absorbed into the bloodstream and carbon dioxide is expelled. This process is driven by differences in partial pressure between the air in the lungs and the blood. Oxygen moves from the air, where its partial pressure is higher, into the blood, where its partial pressure is lower. Conversely, carbon dioxide moves from the blood, where its partial pressure is higher, into the air, where its partial pressure is lower.

At high altitudes, the lower partial pressure of oxygen in the air means that less oxygen is available to move into the blood. This can lead to a condition known as hypoxia, where the body doesn't get enough oxygen. Symptoms of hypoxia can include shortness of breath, rapid heartbeat, and confusion.

The body can adapt to high altitudes over time through a process known as acclimatisation. This involves increasing the number of red blood cells, which carry oxygen, and altering the way that the body uses oxygen. However, this process can take several days or even weeks, and it doesn't completely offset the effects of the lower partial pressure of oxygen.