What are the causes of hyperpolarization ?

Options

A. Due to excess `K^(+)` outflux
B. Due to influx of `Cl^(–)` ions
C. After releasing of GABA
D. All the above

Answer

**Step-by-Step Solution:**

1. **Understanding Hyperpolarization**: Hyperpolarization refers to an increase in the membrane potential of a neuron, making it more negative than the resting potential. This process makes it less likely for the neuron to fire an action potential.

2. **Ion Movement**: The primary causes of hyperpolarization are related to the movement of ions across the neuron's membrane. Specifically, hyperpolarization can occur due to:
- **Excess Potassium Ion Outflux**: When potassium ions (K+) leave the neuron, the inside of the cell becomes more negative, leading to hyperpolarization.
- **Influx of Chlorine Ions**: The entry of chloride ions (Cl-) into the neuron can also contribute to hyperpolarization, as Cl- is negatively charged and increases the negativity inside the cell.

3. **Role of Neurotransmitters**: Certain neurotransmitters, such as gamma-aminobutyric acid (GABA), can facilitate hyperpolarization by opening channels that allow Cl- to enter the cell or by promoting K+ outflux.

4. **Conclusion**: Therefore, the causes of hyperpolarization include:
- Excess potassium ion outflux.
- Influx of chloride ions after the release of GABA.

5. **Final Answer**: The correct options for the causes of hyperpolarization are due to excess potassium ion outflux and due to the influx of chloride ions after the release of GABA.

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