The potential difference across the membrane of a relaxed muscle fibre is called resting potential ,It amounts to about

Options

A. `-70 mV`
B. `50MV`
C. `100 mV`
D. `50-100 mV`

Answer

**Step-by-Step Solution:**

1. **Understanding Resting Potential:**
- Resting potential refers to the potential difference across the membrane of a relaxed muscle fiber. It is a crucial aspect of muscle physiology as it helps maintain the muscle in a relaxed state.

2. **Identifying the Value of Resting Potential:**
- The resting potential is typically measured in millivolts (mV). In muscle fibers, this value is generally around -70 mV. This negative value indicates that the inside of the muscle cell is more negatively charged compared to the outside.

3. **Role of Ion Concentrations:**
- The resting potential is maintained by the differential permeability of the muscle membrane to various ions, primarily sodium (Na+), potassium (K+), and chloride (Cl-). The sodium-potassium pump plays a significant role in this process by actively transporting Na+ out of the cell and K+ into the cell.

4. **Conclusion:**
- Based on the information provided, the potential difference across the membrane of a relaxed muscle fiber, known as resting potential, amounts to approximately -70 mV. Therefore, the correct answer to the question is -70 mV.

**Final Answer:**
The potential difference across the membrane of a relaxed muscle fiber (resting potential) amounts to about **-70 millivolts**.

---