The action of heart includes contractions and relaxations of the atria and ventricles. Contraction of the heart is called systole and relaxation is called diastole. The dynamics of blood flow in blood vessels is no exception and blood flows through the blood vessels along a pressure gradient, always moving from higher to lower pressure areas. Fundamentaly, the pumping action of heart generates blood flow. The contraction of atria is initiated and activated by sinoatrial node (SA node-Pacemaker), which spreads waves of contraction across the wall of atria via muscle fibres at regular intervals.
In humans, blood passes from the post caval to the diastolic right atrium of heart due to
NEET UG 2008 — Zoology Body Fluids and Circulation
2008mcqeasy
In humans, blood passes from the post caval to the diastolic right atrium of heart due to
Official previous-year question
Held on 30 Apr 2008 · Verified 9 Jul 2026.
Options
- A
pushing open of the venous valves
- B
suction pull
- C
stimulation of the sino auricular node
- D
pressure difference between the caval and atrium
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