What is altitude sickness, "Soroche" or "Apunamiento"?...

The Puna is on average 3500 - 3700 meters above sea level. The atmosphere layers at these altitudes contains different percentages gases (oxygen, nitrogen, ozone etc). The human body copes with this new environment by, for example, breathing faster to provide more air into the lungs, and usually the heart rate increases in order to pump more blood and oxygen to the heart.  All this may cause excitement and a sense of lack of oxygen. The height causes a substantial difference in air pressure. A person at sea level supports a column of air equal to a difference of approximately 4000 meters from the same person of the Puna. This decrease in pressure can sometimes cause nausea or fatigue and weak legs. 

If you travel along the Andean slopes it is easy to encounter lots of curves at a high altitude. Particularly in the first day or days of the trip you need to take these tours/trips at low speed and with a few stops, for better acclimatization to altitude and not to suffer from altitude sickness while in the car. 
Doing this we find that the tight curves of mountain paths don´t affect the sensitive organ of sight, which quickly and constantly changes benchmarks. When this does not happen it affects the optic nerve transmission to the optical center in the brain near the neck, which gives you a headache (near the neck) and dizziness.

Source: La Puna Argentina, Ricardo N. Alonso