In saltatory conduction of impulse

Options

A. time is conserved
B. energy is conserved
C. both (1) and (2)
D. either time nor energy is conserved

Answer

### Step-by-Step Solution:

1. **Understanding Saltatory Conduction**:
- Saltatory conduction occurs in myelinated nerve fibers. In these fibers, the myelin sheath insulates the axon, preventing ion flow across the membrane except at specific gaps known as the Nodes of Ranvier.

2. **Role of Nodes of Ranvier**:
- At the Nodes of Ranvier, the axonal membrane is exposed, allowing for the generation of action potentials. The impulse jumps from one node to the next, rather than traveling continuously along the entire length of the axon.

3. **Conservation of Time**:
- Because the impulse jumps between nodes, the conduction of the nerve impulse is much faster compared to unmyelinated fibers where the impulse must travel continuously. This rapid transmission means that less time is required for the impulse to travel along the nerve.

4. **Conservation of Energy**:
- Saltatory conduction also conserves energy. Since the action potentials are generated only at the nodes, less energy is used in maintaining the ion gradients across the entire length of the axon. This results in a lower metabolic cost for the neuron.

5. **Conclusion**:
- Therefore, in saltatory conduction, both time and energy are conserved. The correct answer to the question is that both time and energy are conserved during saltatory conduction.

### Final Answer:
Both time and energy are conserved in saltatory conduction of impulses.