In Myasthenia gravis _______ is affected .

Options

A. Sarcoplasmic reticulum
B. Sarcolemma
C. Neuromuscular junction
D. T-Tubules

Answer

### Step-by-Step Solution

1. **Understanding Myasthenia Gravis**: Myasthenia gravis is an autoimmune disease characterized by weakness and rapid fatigue of voluntary muscles. It occurs when the immune system mistakenly attacks the body's own tissues.

2. **Identifying the Affected Area**: The question asks what is affected in myasthenia gravis. The options provided are:
- Sarcoplasmic reticulum
- Sarcolemma
- Neuromuscular junction
- T-tubule

3. **Analyzing Each Option**:
- **Sarcoplasmic Reticulum**: This structure is responsible for storing calcium ions which are crucial for muscle contraction. It is not primarily affected in myasthenia gravis.
- **Sarcolemma**: This is the plasma membrane surrounding muscle fibers. While it plays a role in muscle function, it is not the primary site of dysfunction in myasthenia gravis.
- **Neuromuscular Junction**: This is the critical area where nerves communicate with muscles. In myasthenia gravis, antibodies attack the receptors at the neuromuscular junction, preventing effective communication and leading to muscle weakness. This is the correct answer.
- **T-tubule**: These structures help in transmitting the action potential into the muscle fiber. They are not specifically affected in myasthenia gravis.

4. **Conclusion**: Based on the analysis, the correct answer is that in myasthenia gravis, the **neuromuscular junction** is affected.

### Final Answer
In Myasthenia gravis, **the neuromuscular junction is affected**.