In the Aconcagua mountain guides, the pO2 decreases with height in the same proportions as atmospheric pressure. At the edge of the sea, it is 160 mmHg, and for example, at 7,000 m (almost the summit of Cº Aconcagua), it is around 50 mmHg, nearly a third! Second, and to relate what was seen above with the human body, we must understand the functioning of our respiratory system.
The respiratory system, among other functions, is responsible for capturing O2 from the air and introducing it into the blood, and expelling carbon dioxide (CO2) from the body, which is the product of the body’s metabolism. That is why it is essential to acclimatize well while climbing Aconcagua. While O2 passes into the blood (enters the body), CO2 passes from the blood into the alveoli (leaves the body). Thanks to the activity of the respiratory muscles, the conduction routes (nasal passages, trachea, bronchi, and bronchioles) lead the air to the site of gas exchange: the alveolus-capillary unit.
This gas exchange, which occurs due to pressure difference, is called hematosis. Considering all these concepts, we can then say that pO2 is the only force that makes oxygen progress from the pulmonary alveoli to the blood of the pulmonary capillaries. From there, it will travel, thanks to the cardiac impulse, to the cells of the whole organism. At altitude, with less pO2, there is less driving force capable of moving oxygen to the pulmonary capillaries. The lower amount of pO2 in the blood is called hypoxemia. Maybe if you do Aconcagua treks instead of an expedition, you will not feel so much discomfort due to the height.
To understand what happens with atmospheric pressure and the human body, we can imagine atmospheric pressure as the weight that the column of air is making on our body. After giving you this information about what happens in the atmosphere at 7000 meters, I want to tell you about an experience.
During a three-day hike. The guides and clients avoid being splashed with mud since it is an avalanche area at that time of year. The warning was a sound similar to that of an airplane, so the guide of our Aconcagua expedition is looking back and can warn that an avalanche is approaching. That is why we ran and did not abandon people to be in a safe zone. These are things that can happen when we work in real natural environments.
This is a classic debris flow – the front is almost arid and mostly large rocks. The tail of the debris flow has more water and more delicate material. Note that the debris flow goes through a series of waves. The weather seems dry and sunny. The minimal debris flow that hikers are crossing at the beginning is also quite intriguing. Even this seems to be rich in debris. I wonder if this is the tail of a previous wave.