Which one is the reason for fast conduction of impulse in heart muscles?

Options

A. Presence of intercalated discs
B. SA node
C. AV node
D. Purkinje fibers

Answer

To answer the question "Which one is the reason for fast conduction of impulse in heart muscles?" we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Cardiac Muscle Structure**:
- Cardiac muscles are unique compared to other muscle types. They are branched and interconnected, which allows for a coordinated contraction of the heart.

**Hint**: Consider how the structure of cardiac muscle differs from skeletal and smooth muscles.

2. **Intercalated Discs**:
- Cardiac muscle fibers are connected by structures known as intercalated discs. These discs are crucial for the functioning of the heart.

**Hint**: Think about what role these connections play in muscle contraction.

3. **Presence of Gap Junctions**:
- Within the intercalated discs, there are specialized connections called gap junctions. These junctions allow for the direct passage of ions and electrical impulses between adjacent cardiac muscle cells.

**Hint**: Reflect on how electrical signals travel through the heart and what facilitates this process.

4. **Fast Conduction of Impulses**:
- The presence of gap junctions in the intercalated discs is the primary reason for the rapid conduction of electrical impulses in cardiac muscle. They enable the heart muscle cells to communicate quickly and efficiently, leading to synchronized contractions.

**Hint**: Consider how the speed of impulse conduction affects heart function.

5. **Conclusion**:
- Therefore, the reason for the fast conduction of impulses in heart muscles is the presence of gap junctions in the intercalated discs.

### Final Answer:
The reason for fast conduction of impulse in heart muscles is the presence of gap junctions in the intercalated discs.