The effects of high altitude on humans are considerable. The percentage saturation of hemoglobin with oxygen determines the content of oxygen in our blood. After the human body reaches around 2,100 m (7,000 feet) above sea level, the saturation of oxyhaemoglobin begins to plummet. However, the human body has both short-term and long-term adaptations to altitude. Athletes use these adaptations to help their performance. There is a limit to the level of adaptation; mountaineers refer to the altitudes above 8,000 meters’ (26,000 ft) as the "death zone", where no human body can acclimatize.
At higher altitudes also, our bodies make adjustments which is creating more red blood cells to carry oxygen through the bloodstream, pushing air into normally unused portions of the lungs and producing citrate synthase, a special enzyme that helps the oxygen found in hemoglobin make its way into body tissue. High altitude also triggers an increase in our heartbeat, breathing and urination. The low humidity and low air pressure at high altitudes causes moisture from our skin and lungs to evaporate at a faster pace and our body's increased exertion requires even more water to keep it hydrated.
Besides that, less of oxygen also can cause a cluster of symptoms called altitude sickness. People living at or visiting high altitudes must learn to breathe more efficiently to avoid altitude sickness. The chronic lack of oxygen at high altitudes can lead to serious, life-threatening illnesses such as pulmonary edema and loss of consciousness. If we traveling to high altitudes for the first time, take several days to make our trip. This gives our body time to gradually acclimate to the decreased available oxygen. Other than that, it can lead to hypoxia, which occurs when the body has insufficient access to oxygen. Our lungs must work harder, and this can result in a variety of physical ailments. Symptoms of hypoxia include difficulty concentrating, headaches, dizziness,