Question

The prime cause of altitude sickness in men due to ascent on high mountains is

• A. Excess of CO${}_2$ in blood
• B. Decreased efficiency of haemoglobin
• C. Decreased partial pressue of oxygen
• D. Decreased proportion of oxygen in air

Answer 1

The correct option is C Decreased partial pressue of oxygen

The barometric pressure decreases at progressively higher altitudes. Because the concentration of oxygen in the air remains at 21%, the partial pressure of oxygen decreases along with the barometric pressure. When a person moves to a high altitude, his or her body adjusts over time by producing a greater number of RBCs. Getting sufficient oxygen from the air becomes an ever increasing problem at higher altitudes. In addition to the problems of hypoxia, a rapid decrease in barometric pressure causes decompression sickness (commonly known as the bends because those suffering from it bend over in pain). When the barometric pressure drops below the total pressure of all gases dissolved in the blood and other body fluids, the dissolved gases tend to come out of solution and form gas bubbles. In the body, nitrogen has a low solubility in blood and tissues. When it comes out of solution, the bubbles formed may damage tissues and block capillaries, interfering with blood flow. The clinical effects of decompression sickness are pain, dizziness, paralysis, unconsciousness, and even death.

Therefore, the correct answer is option C.