Question

Arrange the sequential operation of AV valves:
A. Atria contract, forcing additional blood into ventricles.
B. Chordae tendinae tighten, preventing valve flaps from entering into atria.
C. Ventricles contract, forcing blood against AV valve flaps.
D. Blood returning to the atria puts pressure against AV valves, and valves are forced open.
E. AV valve flaps hang limply into ventricles.

• A. D, E, C, A, B
• B. D, E, A, C, B
• C. D, E, B, C, A
• D. D, E, C, B, A

Hint:

Think “Open → Hang → Atria push → Ventricles push → Chordae tighten” for AV valve sequence.

Answer 1

The Correct Option is B

Step 1: Recall function of AV valves.
Atrioventricular (AV) valves (tricuspid and mitral) regulate blood flow between atria and ventricles, preventing backflow.
Step 2: Sequence of operation.
1. Blood returning to atria increases pressure, forcing AV valves open (D).
2. Once open, valve flaps hang limply into ventricles (E).
3. Atria contract, pushing more blood into ventricles (A).
4. Ventricles then contract, pushing blood against AV valve flaps (C).
5. Chordae tendinae tighten to keep valve flaps closed and prevent backflow (B).
Step 3: Analysis of options.
The correct sequence is D $\rightarrow$ E $\rightarrow$ A $\rightarrow$ C $\rightarrow$ B.
Step 4: Importance.
This sequence ensures unidirectional blood flow — atria to ventricles, then ventricles to arteries, without regurgitation.