Which of the following statements is not correct? +30! -F Membrane Potential (mV) H D. .B -70- A C Time (ms) Label A represents the resting membrane potential Label B represents the threshold potential Voltage-gated Na* channels are closed at the membrane potential labeled H Voltage-gated K* channels are closed at the membrane potential labeled C

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### Understanding Membrane Potentials: Analyzing an Action Potential Graph

**Question 40**

**Which of the following statements is *not* correct?**

**Graph Description:**
The graph shows the changes in membrane potential (mV) over time (ms), highlighting different phases of an action potential in a neuron.

1. **Resting Membrane Potential (Label A)**: This is the state when a neuron is at rest, and the membrane potential is around -70 mV.
2. **Threshold Potential (Label B)**: This is the critical level to which the membrane potential must be depolarized to initiate an action potential.
3. **Depolarization (D to F)**: Upon reaching threshold (Label B), there is a rapid rise in membrane potential, moving towards a more positive value (+30 mV around Label F).
4. **Repolarization (Label G to H)**: After the peak, the membrane potential rapidly falls back towards negative values.
5. **Hyperpolarization (Label H)**: The membrane potential temporarily becomes more negative than the resting potential before stabilizing back to the resting membrane level.

**Options:**

o Label A represents the resting membrane potential  
o Label B represents the threshold potential  
o Voltage-gated Na⁺ channels are closed at the membrane potential labeled H  
o Voltage-gated K⁺ channels are closed at the membrane potential labeled C  

To correctly answer the question, identify which statement does *not* accurately describe what is occurring at the specified points or phases in the graph. 

**Explanation of Correct Answer:**

- **Label A (Resting membrane potential)** is correct, as the resting membrane potential of a neuron is typically around -70 mV.
- **Label B (Threshold potential)** is correct, as the neuron must reach this level to fire an action potential.
- **Voltage-gated Na⁺ channels closed at H** is incorrect. At H (repolarization/hyperpolarization phase), voltage-gated Na⁺ channels would already be inactivated, and it’s the voltage-gated K⁺ channels that open to return the membrane potential towards the negative side.
- **Voltage-gated K⁺ channels closed at C** might create confusion, but considering that C denotes a phase post the peak of action potential, it is more correct compared to H as many K⁺ channels would have closed following the repolarization phase.

Thus, the **incorrect
Transcribed Image Text:### Understanding Membrane Potentials: Analyzing an Action Potential Graph **Question 40** **Which of the following statements is *not* correct?** **Graph Description:** The graph shows the changes in membrane potential (mV) over time (ms), highlighting different phases of an action potential in a neuron. 1. **Resting Membrane Potential (Label A)**: This is the state when a neuron is at rest, and the membrane potential is around -70 mV. 2. **Threshold Potential (Label B)**: This is the critical level to which the membrane potential must be depolarized to initiate an action potential. 3. **Depolarization (D to F)**: Upon reaching threshold (Label B), there is a rapid rise in membrane potential, moving towards a more positive value (+30 mV around Label F). 4. **Repolarization (Label G to H)**: After the peak, the membrane potential rapidly falls back towards negative values. 5. **Hyperpolarization (Label H)**: The membrane potential temporarily becomes more negative than the resting potential before stabilizing back to the resting membrane level. **Options:** o Label A represents the resting membrane potential o Label B represents the threshold potential o Voltage-gated Na⁺ channels are closed at the membrane potential labeled H o Voltage-gated K⁺ channels are closed at the membrane potential labeled C To correctly answer the question, identify which statement does *not* accurately describe what is occurring at the specified points or phases in the graph. **Explanation of Correct Answer:** - **Label A (Resting membrane potential)** is correct, as the resting membrane potential of a neuron is typically around -70 mV. - **Label B (Threshold potential)** is correct, as the neuron must reach this level to fire an action potential. - **Voltage-gated Na⁺ channels closed at H** is incorrect. At H (repolarization/hyperpolarization phase), voltage-gated Na⁺ channels would already be inactivated, and it’s the voltage-gated K⁺ channels that open to return the membrane potential towards the negative side. - **Voltage-gated K⁺ channels closed at C** might create confusion, but considering that C denotes a phase post the peak of action potential, it is more correct compared to H as many K⁺ channels would have closed following the repolarization phase. Thus, the **incorrect
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