NEETZoologyBody Fluids and Circulation
What is the purpose of atrial systole in the heart?
Options
- ATo relax the atria
- BTo increase the flow of blood into the ventricles
- CTo stimulate the ventricular muscles to contract
- DTo close the semilunar valves
Correct answer
B. To increase the flow of blood into the ventricles
Step-by-step solution
The ventricles now relax (ventricular diastole) and the ventricular pressure falls causing the closure of semilunar valves which prevents the backflow of blood into the ventricles. As the ventricular pressure declines further, the tricuspid and bicuspid valves are pushed open by the pressure in the atria exerted by the blood which was being emptied into them by the veins. The blood now once again moves freely to the ventricles. The ventricles and atria are now again in a relaxed (joint diastole) state, as earlier.