Q. In humans, blood passes from the post caval to the diastolic right atrium of heart due to
A) Pressure difference between the post caval and atrium
B) Pushing open of the venous valves
C) Suction pull
D) Stimulation of the sino auricular node
Explanation
[Solution from source] During atrial diastole the pressure in the right atrium falls below that in the venae cavae, so blood flows down this pressure gradient into the atrium. SA node stimulation starts contraction (systole), not the filling of a relaxed atrium. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.