Which one of the following is a matching pair ?

Options

A. a) Lub - sharp closure of AV valves at the beginning of ventricular systole
B. b) Dup- sudden opening of smilunar valves at the beginning og ventricular diastole
C. c) Pulsation of the radial artery- valves in the blood vessels
D. d) Initiation of the heart beat - Purkinje fibres

Explanation

To solve the question, "Which one of the following is a matching pair?", we will analyze each option provided and determine which one accurately describes a relationship in cardiac activity.

### Step-by-Step Solution:

1. **Understanding the Terms**:
- We need to identify what "lub" and "dub" refer to in the context of heart sounds. "Lub" (S1) is associated with the closure of the atrioventricular (AV) valves, while "dub" (S2) is associated with the closure of the semilunar valves.

2. **Analyzing Option A**:
- Option A states: "Lub is a sharp closure of AV valves at the beginning of ventricular systole."
- During ventricular systole, the ventricles contract, and the AV valves close to prevent backflow of blood into the atria. This closure produces the "lub" sound. Therefore, this statement is correct.

3. **Analyzing Option B**:
- Option B states: "Dub is a sudden opening of semilunar valves at the beginning of ventricular systole."
- This is incorrect because the "dub" sound occurs when the semilunar valves close at the end of ventricular systole, not when they open.

4. **Analyzing Option C**:
- Option C states: "Pulsation of radial artery is related with the valves in the blood vessels."
- This is also incorrect. The pulsation of the radial artery is due to the pressure wave generated by the heartbeat, not directly related to valves in the blood vessels.

5. **Analyzing Option D**:
- Option D states: "Initiation of heartbeat is caused by Purkinje fibers."
- This statement is incorrect because the heartbeat is initiated by the sinoatrial (SA) node, not the Purkinje fibers. The Purkinje fibers are responsible for conducting the impulse throughout the ventricles after it has been initiated by the SA node.

6. **Conclusion**:
- After analyzing all options, the only correct statement is Option A: "Lub is a sharp closure of AV valves at the beginning of ventricular systole." Therefore, Option A is the matching pair.

### Final Answer:
The correct matching pair is **Option A**: "Lub is a sharp closure of AV valves at the beginning of ventricular systole."

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