Rate of conduction of impulse will be faster in case of

Options

A. Myelinated nerve fibre
B. Thicker nerve fibre
C. Non-myelinated nerve fibre
D. Both (1) and (2)

Answer

To determine the rate of conduction of impulses in nerve fibers, we need to consider two main factors: the presence of myelin and the diameter of the nerve fiber. Let's break down the solution step by step.

### Step-by-Step Solution:

1. **Understanding Nerve Fibers**:
- Nerve fibers can be classified into two types: myelinated and non-myelinated. Myelinated fibers have a fatty insulating layer called myelin, while non-myelinated fibers do not.

**Hint**: Remember the difference between myelinated and non-myelinated fibers.

2. **Role of Myelin**:
- Myelin acts as an insulator. It prevents the loss of electrical signals and allows for faster conduction of impulses. In myelinated fibers, the action potential occurs only at the nodes of Ranvier, which are small gaps in the myelin sheath.

**Hint**: Think about how insulation affects electrical conduction in wires.

3. **Saltatory Conduction**:
- In myelinated fibers, impulses jump from one node of Ranvier to the next in a process called saltatory conduction. This makes the conduction of impulses much faster compared to non-myelinated fibers, where the impulse must travel continuously along the entire length of the fiber.

**Hint**: Visualize how jumping from one point to another can be quicker than moving continuously.

4. **Effect of Diameter**:
- The diameter of the nerve fiber also influences conduction speed. Thicker fibers conduct impulses faster than thinner fibers because they have less resistance to the flow of ions.

**Hint**: Consider how a wider pipe allows water to flow more easily than a narrower one.

5. **Conclusion**:
- Given the options: myelinated nerve fiber, thicker nerve fiber, non-myelinated nerve fiber, and both one and two, the fastest conduction of impulses will occur in myelinated nerve fibers due to both the presence of myelin and potentially a larger diameter.

**Hint**: Focus on which option combines both factors that enhance conduction speed.

### Final Answer:
The rate of conduction of impulse will be faster in the case of **myelinated nerve fibers**.