Q158 / 200 · NEET 2022 (Phase 1) · Zoology
Which one of the following statements is correct?
- AThe tricuspid and the bicuspid valves open due to the pressure exerted by the simultaneous contraction of the atria
- Correct answerBBlood moves freely from atrium to the ventricle during joint diastole
- CIncreased ventricular pressure causes closing of the semilunar valves
- DThe atrio-ventricular node (AVN) generates an action potential to stimulate atrial contraction
Solution
Contraction of heart chambers is called systole and
relaxation is called diastole. Atria and ventricles contract alternately.
Right atrium receives deoxygenated blood and left atrium receives oxygenated blood. When both the atria are completely filled with blood, pressure is exerted on the wall due to which SA node gets excited and generates cardiac impulse. This leads to atrial systole. During atrial systole, blood is pumped into ventricles.
The opening between the right atrium and the right ventricle is guarded by the tricuspid valve, whereas a bicuspid valve guards the opening between the left atrium and the left ventricle.
So, during atrial systole, the bicuspid and tricuspid valves are open, and the pulmonary/aortic semilunar valves are closed.
Hence, the correct answer is option: 'B'.