Zoology - Body Fluids and Circulation Question with Solution | TestHub

As a person moves up a hill the $p{\mathrm{O}}_2$ and total atmospheric pressure decreases. Decrease in $p{\mathrm{O}}_2$ due to increasing altitude, stimulates the JG-cells of kidney to secrete erythropoietin hormone, increasing the number of RBCs (polycythemia) to compensate the supply of ${\mathrm{O}}_2$. At higher altitude, haemoglobin has lower binding affinity to ${\mathrm{O}}_2$ because the primary factor responsible for binding is $p_2$, which decreases at higher altitude.