NEET2012ZoologyBody Fluids and CirculationActual
People who have migrated from the planes to an area adjoining Rohtang Pass about six months back
Options
- Ahave more RBCs and their haemoglobin has a lower binding affinity to O ₂
- Bare not physically fit to play games like football
- Csuffer from altitude sickness with symptoms like nausea, fatigue, etc.
- Dhave the usual RBC count but their haemoglobin has very high binding affinuty to O ₂
Correct answer
A. have more RBCs and their haemoglobin has a lower binding affinity to O ₂
Step-by-step solution
As a person moves up a hill the p O ₂ and total atmospheric pressure decreases. Decrease in p 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 O ₂ . At higher altitude, haemoglobin has lower binding affinity to O ₂ because the primary factor responsible for binding is p₂ , which decreases at higher altitude.