Node of Ranvier occurs where

Options

A. Neurilemma is discountinuos
B. Myelin sheath is discontinuos
C. Both neurilemma and myelin sheath are discountinuos
D. Covered by myelin sheath

Answer

**Step-by-Step Solution:**

1. **Understanding Neurons**: Neurons are the functional units of the nervous system, responsible for transmitting signals throughout the body. They consist of a cell body, dendrites, and an axon.

2. **Myelin Sheath**: The axon of many neurons is covered by a fatty layer known as the myelin sheath. This sheath is formed by specialized cells called Schwann cells.

3. **Discontinuity of Myelin Sheath**: The myelin sheath is not continuous along the entire length of the axon. Instead, it has gaps or interruptions. These gaps are crucial for the function of the neuron.

4. **Node of Ranvier**: The gaps in the myelin sheath are referred to as the Nodes of Ranvier. These nodes occur where the myelin sheath is discontinuous and the neurolemma (the outer membrane of the Schwann cells) is also discontinuous.

5. **Function of Nodes of Ranvier**: The presence of Nodes of Ranvier allows for faster transmission of electrical signals along the axon. This is because the signal can jump from one node to the next, a process known as saltatory conduction.

6. **Conclusion**: Therefore, the Node of Ranvier occurs where the myelin sheath and neurolemma are discontinuous along the axon of a neuron.

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