Altitude

The concentration of oxygen at sea level is about 21% and the barometric pressure averages 760 mmHg. As altitude increases, the concentration remains the same but the number of oxygen molecules per breath is reduced. At 12,000 feet, the barometric pressure is only 483 mmHg, so there are roughly 40% fewer oxygen molecules per breath. In order to properly oxygenate the body, your breathing rate (even while at rest) has to increase. This extra ventilation increases the oxygen content in the blood, but not to sea level concentrations. Since the amount of oxygen required for activity is the same, the body must adjust to having less oxygen.

However, besides being constantly out of breath, there are several other side effects high altitude brings on:

• Increased appetite – this is due to the increase in the body’s base metabolic rate while exercising at altitude. Put simply, the body must work harder at altitude therefore it requires more energy intake in the form of food.
• Increased bladder activity – as carbon dioxide levels are higher at altitude there will be higher than normal levels of carbon dioxide in the bloodstream. A byproduct of this higher than usual concentration of carbon dioxide is an increase of sodium bicarbonate in the bladder and body. In order to excrete the increased levels of sodium bicarbonate more frequent urination than normal is required. (This particular side effect really hits home, because public restrooms in Cusco are almost impossible to find. They are usually holes in the ground or toilet stalls with urine all over the floor and feces all over the toilet bowl.)
  
• Insomnia
• Swelling of the face, hands, feet and/or knees with a weight gain of 4-12 pounds, mostly occurring in women. Cute.
• Sunburn- there is less atmosphere to block out the sun's burning ultraviolet rays, so sunburn occurs more readily. Again, this one really hits home with my skin.
• Brain executive function: in a study of nine mountain climbers, six of the nine climbers had lower than average scores on the Digit Symbol test, which measures executive functions such as the ability to anticipate outcomes and adapt to changing situations.
• Memory: the same climbers scored lower than average on the Prose Memory test (immediate recall) and on the Rey's Figure test (delayed recall).
• Weakened immune system because of the lack of oxygen in the air. As a result, it's significantly easier to get sick (like my poor friend Alex who has a vicious sinus infection that won't go away) and much harder to get better.
• Increased gas and flatulence.... yeah.

I took this picture on a hike Alex and I went on over the weekend... hopefully you can sense the proximity to the clouds and thus our incredibly high altitude which interferes in our lives in oh so many ways!

Happy St. Patrick's Day!