Which two of the following changes $(1-4)$ usually tend to occur in the plain dwellers when they move to…
Which two of the following changes $(1-4)$ usually tend to occur in the plain dwellers when they move to high altitudes $(3,500 \mathrm{~m}$ or more)?
(1) Increase in red blood cell size
(2) Increase in red blood cell production
(3) Increased breathing rate
(4) Increase in thrombocyte count Changes occurring are
(2) and (3)
(3) and (4)
(1) and (4)
(1) and (2)
Solution
When a person moves to higher altitudes, the $\mathrm{P}_{\mathrm{O}_2}$ and total atmospheric pressure decrease. Hypoxia stimulates the JG-cells of the kidney to release erythropoietin hormone, which stimulates erythropoesis in bone marrow causing polycythemia. Hypoxia will also increase breathing rate. Initially the size of RBCs will also increase but with increase in number of RBCs, the size of RBCs becomes normal.