People who stay in the highest mountains expose themselves to great risks because extreme height is lethal.

Altitude sickness

The height kills the organism. Brain, muscle and other tissues won’t work without oxygen. When height make oxygen levels fall, the body activates a number of defense mechanisms, which ultimately are fatal.

• The lungs expand

  When the body detects that it gets less oxygen, it expands the lungs, and the heart begins to beat faster to get more oxygenated blood distributed in the body.

• The bone marrow produces blood

  The bone marrow increases production of red blood cells that transports oxygen from the lungs to all tissues.

• Blood becomes thick

  The extra blood cells thicken the blood. The risk of both thrombosis and bleeding increases.

• The brain swells

  The brain responds to the lack of oxygen by widening the blood vessels that lead oxygen to the brain cells. The enlarged blood vessels make the brain swell and push against the skull.

• The lungs collapse

  The lungs have about 300 million pulmonary alveoli, which together have the same surface as half a tennis court. The enlarged and hard pumping lungs destroy the thin membrane that separates the arteries and veins from the alveoli. When the membrane breaks the lungs are filled with blood and the climber drowns.

How you react to high altitudes

8000 m: the Zone of Death

No humans can handle the minimal amount of oxygen at 8000 meters for long. Climbers risk of injury for life.

• Chronic fatigue and dizziness
• Risk of brain damage
• Chronic respiratory problems

3500 m: Danger Zone

Climbers who ignore the early symptoms are in mortal danger. They must be moved to a lower altitude or death can enter in less than 24 hours.

• Extreme fatigue
• Blurred vision and severe headaches
• Problems with motor skills

2500 m: Acute altitude sickness

After a few hours at high altitude the first symptoms occur. The acute altitude sickness often disappears after a day of adjustment.

• Dizziness and fatigue
• Headache
• Loss of appetite, nausea and vomiting

The cells dry out

The cold causes the cells to freeze-dry. When the body is exposed to extreme cold, it will cut the blood supply to the body’s external parts. The reaction can cause severe tissue damage.

1. The nerves send messages to the brain that it is exposed to strong cooling.
2. The brain responds to the threat by sending a signal to the blood vessels that they should contract and just feed vital organs such as heart, liver and lungs.
3. Without heat from the blood the body surface quickly cools down to the outside temperature.
4. The water contained in the tissue freezes to ice crystals, which grow by drawing water out of each cell. At this stage toes and fingers, etc., can be saved if they thawed.
5. However if the hand continues to be frozen the entire cells will freeze. Gradually, the ice expands so much that the cells burst and the tissues die. If the freezing continues even muscles, nerves and bone will be damaged.

The body’s organs fall into a coma

People who are cooled to below 32 degrees Celsius are in danger of falling into hypothermic coma – a condition where the body shuts down all functions to protect itself.

1. The pupils dilate and the eyes seem completely lifeless.
2. The thyroid gland slows burning to conserve heat. The body stops shaking to save energy.
3. The lungs decrease oxygen supply.
4. The heart beats as infrequently as twice a minute – and the blood supply to less important organs ceases.
5. The skin becomes gray and eventually almost snow white.

Insect can handle minus 40 degrees Celsius

While the cold is dangerous for the human body there are animals that thrive at extreme sub-zero temperatures. For example, the Antarctic springtails survives a temperature of minus 40 degrees Celsius, simply by emptying its body of fluid and thereby prevents the cells from freezing.

Mysterious gene makes Sherpa’s invulnerable

An international research team has isolated a gene that makes the human body adapt to living at high altitude. The gene is for instance widespread in the population of Himalayas Sherpa population.  When a Sherpa climbs to high altitudes and lower oxygen levels the gene prevents altitude sickness by preventing the increasing production of red blood cells.