Which of the following act is responsible for the depolarisation of the neuron ?

Options

A. Opening of voltage gated `K^(+)` channel
B. Opening of voltage gated `Na^(+)` channel
C. Closure of voltage gated `K^(+)` channel
D. Closure of voltage gated `Na^(+)` channel

Answer

To determine which act is responsible for the depolarization of a neuron, we need to understand the process of depolarization and the role of ion channels in this process.

### Step-by-Step Solution:

1. **Understanding Depolarization**:
- Depolarization is a change in the membrane potential of a neuron, making it less negative (or more positive). This is crucial for the generation of an action potential.

2. **Role of Ion Channels**:
- Neurons have specific ion channels that open in response to stimuli. The two main types of ion channels involved in depolarization are sodium (Na⁺) and potassium (K⁺) channels.

3. **Identifying the Options**:
- The options provided are:
1. Opening of voltage-gated potassium ion channels
2. Opening of voltage-gated sodium ion channels
3. Closure of voltage-gated potassium ion channels
4. Closure of voltage-gated sodium ion channels

4. **Analyzing Each Option**:
- **Option 1**: Opening of voltage-gated potassium ion channels - This would lead to hyperpolarization, not depolarization.
- **Option 2**: Opening of voltage-gated sodium ion channels - This allows sodium ions to flow into the neuron, causing depolarization.
- **Option 3**: Closure of voltage-gated potassium ion channels - This does not directly cause depolarization; it may contribute to the process after depolarization.
- **Option 4**: Closure of voltage-gated sodium ion channels - This would stop depolarization and lead to repolarization.

5. **Conclusion**:
- The correct answer is **Option 2: Opening of voltage-gated sodium ion channels**. This action allows sodium ions to enter the neuron, resulting in depolarization.