Multiple Choice
In the diagram of a typical neuron, which letter indicates the region where neurotransmitters are released?
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45. Nervous System
Neurons and Action Potentials
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In a neuron, the opening of sodium ($\mathrm{Na^+}$) gates typically leads to:
A
Repolarization of the membrane
B
Inhibition of action potential generation
C
Hyperpolarization of the membrane
D
Depolarization of the membrane
Verified step by step guidance1
Understand the role of sodium ($\mathrm{Na^+}$) in neuronal activity: Sodium ions are positively charged and are more concentrated outside the neuron compared to the inside at rest. This creates a concentration gradient and an electrical gradient.
Recognize what happens when sodium ($\mathrm{Na^+}$) gates open: When these gates open, sodium ions move into the neuron due to the concentration and electrical gradients, making the inside of the neuron less negative.
Define depolarization: Depolarization occurs when the membrane potential becomes less negative (moves closer to zero) compared to the resting membrane potential, which is typically around -70 mV.
Connect the influx of sodium ($\mathrm{Na^+}$) to depolarization: The entry of positively charged sodium ions reduces the negative charge inside the neuron, leading to depolarization of the membrane.
Conclude why depolarization is the correct answer: The opening of sodium gates directly causes depolarization, as it shifts the membrane potential toward a more positive value, which is a key step in the generation of an action potential.
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