Which is a communicating junction which allows the cells to contact as a unit in the heart ?

Options

A. Intercalated disc
B. Gap junction
C. Desmosome
D. Intercellular bridges

Answer

To solve the question "Which is a communicating junction which allows the cells to contact as a unit in the heart?" we will analyze the options provided and understand the role of each type of junction in cardiac tissue.

### Step-by-Step Solution:

1. **Understanding the Types of Junctions**:
- The question provides four options: intercalated disc, gap junction, desmosome, and intercellular bridges. We need to identify which of these serves as a communicating junction in the heart.

2. **Intercalated Discs**:
- Intercalated discs are specialized structures found in cardiac muscle tissue. They contain several types of junctions, including gap junctions and desmosomes. However, they are not a single type of junction themselves.

3. **Desmosomes**:
- Desmosomes are a type of junction that provides mechanical strength by anchoring adjacent cells together. They connect the cytoskeletons of neighboring cells but do not facilitate communication between cells.

4. **Gap Junctions**:
- Gap junctions are specialized channels that allow direct communication between adjacent cells. They enable the passage of ions and small molecules, which is crucial for the synchronized contraction of cardiac muscle cells. This allows the heart to function as a unit.

5. **Intercellular Bridges**:
- Intercellular bridges are structures that facilitate the exchange of cytoplasm between adjacent cells. However, they are not primarily responsible for electrical communication.

6. **Conclusion**:
- Given the functions of each type of junction, the correct answer to the question is **gap junction**. Gap junctions are the communicating junctions that allow cardiac muscle cells to work together as a coordinated unit.

### Final Answer:
**Gap Junction**