Heart of heart' is

Options

A. SA node
B. AV node
C. Bundle of His
D. Purkinje fibres

Answer

### Step-by-Step Text Solution:

1. **Understanding the Term "Heart of Heart":**
- The phrase "heart of heart" refers to a specific part of the heart that plays a crucial role in its functioning.

2. **Identifying the Structure:**
- The structure referred to as the "heart of heart" is the **sinoatrial node (SA node)**.

3. **Function of the Sinoatrial Node:**
- The sinoatrial node is a specialized group of cardiac muscle cells that generates electrical impulses. This is essential for initiating the heartbeat.

4. **Characteristics of the Sinoatrial Node:**
- The SA node is known for its **auto-rhythmicity**, meaning it can generate action potentials (electrical impulses) on its own without external stimuli.

5. **Rate of Impulse Generation:**
- The sinoatrial node typically generates **70 to 75 impulses per minute**, which sets the pace for the heart rate.

6. **Role as the Pacemaker:**
- Due to its ability to generate impulses and regulate the heart rhythm, the sinoatrial node is often referred to as the **pacemaker of the heart**.

### Final Answer:
The "heart of heart" is the **sinoatrial node (SA node)**, which acts as the pacemaker of the heart, generating 70 to 75 impulses per minute due to its auto-rhythmic properties.

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