Which valve prevents the backflow of blood into the right ventricle when the ventricular valve muscle relaxes?

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Applied Anatomy

Medium

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Explanation

The pulmonary valve is a semilunar valve located at the exit of the right ventricle, leading into the pulmonary artery.
During ventricular relaxation (diastole), the pressure in the right ventricle falls below the pressure in the pulmonary artery.
This pressure gradient causes the pulmonary valve to close firmly, preventing the regurgitation (backflow) of blood into the right ventricle.
This action ensures a unidirectional flow of deoxygenated blood towards the lungs.

Option A: The tricuspid valve is an atrioventricular (AV) valve. It prevents backflow from the right ventricle into the right atrium, and this occurs during ventricular contraction (systole), not relaxation.
Option B: The bicuspid (or mitral) valve is located on the left side of the heart. It prevents backflow from the left ventricle into the left atrium during ventricular contraction (systole).
Option D: The pulmonary artery is a major blood vessel, not a valve. It is the structure that receives blood from the right ventricle and carries it to the lungs. The pulmonary valve is located at the entrance to this artery.

Clinical Relevance

Nursing practice connection: Prioritize focused assessment, early escalation, and real-time monitoring when managing Function of heart valves and the cardiac cycle in acute care settings.
In a clinical setting, a faulty pulmonary valve can lead to pulmonary regurgitation, where blood leaks back into the right ventricle. This increases the workload on the right side of the heart and can eventually lead to right-sided heart failure, characterized by symptoms like peripheral edema and jugular venous distension.
The closure of the pulmonary and aortic valves creates the second heart sound (S2). A 'split S2' sound heard on auscultation can indicate physiological changes or pathological conditions like a delayed closure of the pulmonary valve.
What if? If the pulmonary valve becomes stenotic (stiff and narrowed), the right ventricle must work much harder to pump blood through it. This leads to right ventricular hypertrophy (enlargement of the muscle) and can also progress to heart failure.

How to Approach the Question

First, break down the question. Identify the key anatomical location ('right ventricle') and the physiological action ('prevents backflow' when the ventricle 'relaxes').
Recall the two main phases of the cardiac cycle: systole (contraction) and diastole (relaxation). The question specifies relaxation (diastole).
Visualize or recall the path of blood through the heart. Blood flows from the right atrium, through the tricuspid valve, into the right ventricle.
From the right ventricle, blood is pumped out into the pulmonary artery. The valve at this exit point must prevent backflow when the ventricle relaxes.
This identifies the pulmonary valve as the correct structure.
Evaluate the other options. The tricuspid valve is an inflow valve for the right ventricle. The bicuspid valve is on the left side of the heart. The pulmonary artery is a blood vessel, not a valve.

Concept Tested & Keywords

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E6 Anatomy Applied Ashalatha 4e pp. 164-166, 163-165