Store house of `Ca^(+2)` in muscle fibre is____

Answer

**Step-by-Step Solution:**

1. **Understanding Muscle Fibers**: Muscle fibers are specialized cells that facilitate movement in the body. They contain various organelles that help in muscle contraction.

2. **Identifying the Role of Calcium Ions**: Calcium ions (Ca²⁺) play a crucial role in muscle contraction. When a muscle fiber is stimulated, calcium ions are released, which triggers the contraction process.

3. **Locating the Storehouse of Calcium Ions**: The organelle responsible for storing calcium ions in muscle fibers is the sarcoplasmic reticulum. This is a specialized form of the endoplasmic reticulum found in muscle cells.

4. **Mechanism of Calcium Release**: When a neural signal reaches the muscle fiber, it causes the sarcoplasmic reticulum to release calcium ions into the sarcoplasm (the cytoplasm of muscle cells). This release is essential for initiating muscle contraction.

5. **Conclusion**: Therefore, the storehouse of calcium ions in muscle fibers is the sarcoplasmic reticulum.

**Final Answer**: The storehouse of Ca²⁺ in muscle fiber is the **sarcoplasmic reticulum**.

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