Effect of hyperventilation on the oxygen binding affinity of hemoglobin | MDS entrance preaparations

What effect does hyperventilation have on the oxygen binding affinity of hemoglobin-

A.P02 and 02 affinity decrease                                      

B.PO, and O, affinity increase

C.PO, decreases and O, affinity increases                   

D.P02 increases and 02 affinity decreases

Ans. [(B) 

•          During hyperventilation C0₂ washes out, PC0₂ falls, P0₂ increases. As a result, Hb does not release oxygen and the affinity of Hb for oxygen increases.

•          Cheyne-Stokes breathing is seen in voluntary hyperventilation.

-          Cheyne-Stokes breathing is caused by a fall of PC0₂ in blood feeding the medullary respiratory centre.

-          Blood C0₂ is low, there is no stimulation of central chemoreceptor cells in medulla and apnea follows.

PC0₂ rises again and the respiration resumes, but if the PC0₂ now is even slightly higher than normal, there will be a short phase of hyperpnoea followed by apnea