Tachycardia and Hypoxia | PGI MCQs for MD MS Preparations

Tachycardia is caused by hypoxia due to:
A. Reflexely through peripheral chemoreceptors                
B. Diffuse vasodilatation
C. Through central chemoreceptor                                          
D. Secondarily after by hyperventilation

Ans. B 

·         In hypoxia, with the reticulum of PO2 cerebral blood flow increases (due to vasodilation) to maintain O2 delivery in the brain.

Effects of Hypoxia

·         Cerebral blood flow:

·         Increases if PaO2 decreases.

·         If ↓ PaO2 is associated with hyperventilation: cerebral blood flow falls & hypoxia intensified.

·         Synaptic discharge: Increases by directly stimulating the vasomotor center.

·         Lactic acidosis: In hypoxia a large proportion of pyruvate is reduced to lactic acid. (Glucose is broken down to pyruvate under condition & generates ATP)