Q.How the body makes long-term adjustments when living at high altitude ?

Over days to weeks at high altitude, the body makes long-term physiological adjustments — more red blood cells, more haemoglobin, deeper/faster breathing, and better tissue-level oxygen delivery/use — that together improve its ability to survive the low partial pressure of oxygen at altitude.

At high altitude, the same percentage of oxygen is present in the air, but its partial pressure is lower because overall atmospheric pressure is lower, so less oxygen diffuses into the blood at the lungs with each breath. Over time (days to weeks) the body makes several long-term adjustments to cope:

1. Increased red blood cell (RBC) production — the low oxygen level is sensed by the kidney, which secretes more of the hormone erythropoietin; this stimulates the bone marrow to produce more red blood cells (polycythemia), increasing the blood's total oxygen-carrying capacity.

2. Increased haemoglobin content — along with more RBCs, total haemoglobin in the blood rises, allowing more oxygen to be bound and transported per unit volume of blood.

3. Increased pulmonary ventilation — breathing rate and depth (and over time, lung/vital capacity) increase, so more air (and hence more total oxygen) is moved in and out of the lungs per minute, partly compensating for the lower oxygen pressure in each breath.

4. Increased capillary density in tissues — more capillaries develop in body tissues, shortening the diffusion distance from blood to cells and improving oxygen delivery.

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