Why Tibetan People Able to Survive in the High Altitude
Geography of Tibet
Known as the “Roof of the World”, a rich and beautiful land, Tibet is the highest plateau on this earth, with an average altitude of 16,000 feet (4950 meters). Famous for its beauty and ancient history, Tibet is located at the main part of Qinhai-Tibet plateau, southwest frontier of China. The geography of Tibet consists of the high mountains, rivers and lakes lying between Central, East and South Asia. The climate is harsh (especially for those who are not used to it), with thin air, intense sunlight, ultraviolet radiation and insufficient oxygen.
Climate - Altitude Sickness or Hypoxia
Usually an altitude over 9,843 feet (3,000 meters) is defined as high altitude. Most places in Tibet are higher than this level, therefore Altitude Sickness, also called Acute Mountain Sickness (AMS) is the biggest health risk to many tourists in Tibet. This illness is also known as hypoxia – a lack of oxygen to the tissue in your body. The symptoms include headache, dizziness, fatigue, loss of appetite, vomitting, nausea, confusion, breathlessness and lethargy. It can also be fatal. Most people will experience one or more of these symptoms upon their arrival in Tibet. For those who were struck by altitude sickness may wonder how Tibetan people can live at such high altitudes without suffering altitude sickness themselves.
Definition of High Altitude:
1500 to 3500 m (High Altitude)
3500 to 5500 m (Very High Altitude)
above 5500 m (Extreme Altitude)
High Altitude Adaptation
According to the researchers, Tibetans actually are hypoxic, however, their bodies have developed a unique way of dealing with lower atmospheric pressure. If you ask how, then you need to understand why we shouldnt be able to thrive at such high elevations. The oxygen-distribution system of human body has developed over hundreds of millions of years. When we inhale oxygen into our lungs, the oxygen is transferred to blood which then distributes it via hemoglobin (part of our blood that carries oxygen).
Actually, there is about the same amount of oxygen in the air regardless of elevation (around 21%). Since there is a lack of atmospheric pressure at high altitudes, our lungs have more difficulty in absorbing the oxygen. The cardiopulmonary system (the lungs and heart working together to get oxygen to our body) has to work overtime at high altitudes in order to get enough oxygen for our body. This leads to high blood pressure or hypertension.
It is believed by anthropologists that since human body developed near or at sea level, therefore they have difficulty coping with the thin air at high altitudes. The researchers discovered that the people of Tibet exhale much less nitric oxide, their lungs also transferred twice the amount of nitric oxide to their bloodstreams from their lung walls. It is said that nitric oxide causes widening of the blood vessel. Because of this, the blood flows more easily and allows the heart to work at a normal pace. This also means that their hearts have the ability to deliver more of the lower ambient oxygen that is available in the air to the their bodies.
What is not known yet is that whether the high levels of nitric oxide (NO) they have are due to a genetic mutation or whether all people from lower altitude would also gradually adapt similarly after living for prolongedd periods at high altitudes.