Which of the following generates the action potential in the heart ?

Options

A. Right atrium
B. SA node
C. Mitral valve
D. Chordae tendinae

Answer

To answer the question "Which of the following generates the action potential in the heart?", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Key Structure**: The heart has a specialized tissue known as the nodal tissue, which is responsible for generating action potentials.

2. **Focus on the Sinoatrial Node (SA Node)**: The primary structure that generates the action potential in the heart is the Sinoatrial (SA) node. This node is often referred to as the pacemaker of the heart.

3. **Location of the SA Node**: The SA node is located in the right atrium of the heart, specifically at the upper part of the right atrium.

4. **Function of the SA Node**: The SA node generates action potentials approximately every 0.8 seconds, which initiates the cardiac cycle. This action potential spreads through the heart, leading to atrial contraction.

5. **Atrial Contraction**: The action potential generated by the SA node causes depolarization of the atria, resulting in atrial contraction, also known as atrial systole.

6. **Conclusion**: Therefore, the SA node is the correct answer to the question regarding which structure generates the action potential in the heart.

### Final Answer:
The Sinoatrial (SA) node generates the action potential in the heart.

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