Your eyes while climbing Everest

In order to supply your body with enough oxygen to maintain functioning, your heart must work harder. You will have an increased heart rate and greater force per beat. Your body creates more oxygen-carrying red blood cells, which is generally helpful.

However, it also thickens your bloo...

As you climb, less oxygen in your blood means less oxygen in your brain.

At 15,000 feet, your cognitive performance, mood, and central nervous system functioning start to lessen. In severe cases, being at high altitude for long periods or without first acclimatizing, you are at a hig...

If you ascend without proper acclimatization, at around 9,000 feet, your lungs may begin to swell because the blood vessels constrict. Symptoms include a persistent cough and labored breathing.

If the swelling in your lungs worsens, high-altitude pulmonary edema (HAPE) can occur. Symptoms ...