In a neuron, a membrane potential of –90 mV is considered __________.

• A. a normal resting potential
• B. a graded potential
• C. hyperpolarized
• D. depolarized

Answer: (C)

Verified step by step guidance

1. Understand the concept of membrane potential: Membrane potential refers to the voltage difference across a cell's plasma membrane. It is crucial for the function of neurons and muscle cells.
2. Identify the typical resting membrane potential: In most neurons, the normal resting membrane potential is around –70 mV. This is the baseline state when the neuron is not actively sending a signal.
3. Define hyperpolarization: Hyperpolarization occurs when the membrane potential becomes more negative than the resting potential. This means the inside of the neuron is more negatively charged compared to the outside.
4. Compare the given membrane potential to the resting potential: A membrane potential of –90 mV is more negative than the typical resting potential of –70 mV, indicating that the neuron is in a hyperpolarized state.
5. Conclude the analysis: Since the membrane potential is more negative than the resting potential, the correct term to describe this state is 'hyperpolarized.'