Conduction of nerve impulse depends upon

Options

A. Myelin sheath
B. Temperature
C. Diameter of nerve fibre
D. All of these

Answer

### Step-by-Step Solution:

1. **Understanding Nerve Impulse Conduction**: The conduction of nerve impulses is a complex process that involves the transmission of electrical signals along neurons. This process is influenced by several factors.

2. **Role of Myelin Sheath**: The myelin sheath is a fatty layer that surrounds the axons of many neurons. It acts as an insulator, preventing the loss of electrical signals and allowing for faster transmission of impulses. The presence of myelin sheath increases the speed of nerve impulse conduction through a process known as saltatory conduction, where the impulse jumps from one node of Ranvier to the next.

3. **Effect of Temperature**: Temperature also plays a significant role in the conduction of nerve impulses. Higher temperatures can increase the speed of nerve conduction. This is because increased temperature enhances the kinetic energy of the ions involved in the action potential, leading to faster depolarization and repolarization of the neuron.

4. **Diameter of Nerve Fiber**: The diameter of the nerve fiber is another critical factor. Larger diameter fibers have less resistance to the flow of ions, which allows for faster conduction of nerve impulses. This is why myelinated fibers, which are typically larger in diameter, conduct impulses more rapidly than unmyelinated fibers.

5. **Conclusion**: Given the above points, we can conclude that the conduction of nerve impulses depends on:
- The presence of myelin sheath
- The temperature of the environment
- The diameter of the nerve fiber

6. **Final Answer**: Therefore, the correct answer to the question "Conduction of nerve impulse depends upon" is that it depends on all of the mentioned factors.