Multiple Choice
How does a neuron transport enzymes produced in the neurosoma to its axon terminals?
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45. Nervous System
Neurons and Action Potentials
Multiple Choice
Which of the following is an example of an excitatory postsynaptic potential (EPSP) in a typical neuron?
A
Inhibition of voltage-gated Ca\(^{2+}\) channels at the presynaptic terminal
B
Opening of ligand-gated Cl\(^-\) channels causing membrane hyperpolarization
C
Activation of voltage-gated K\(^+\) channels leading to repolarization
D
Opening of ligand-gated Na\(^+\) channels causing membrane depolarization
Verified step by step guidance1
Step 1: Understand the concept of an excitatory postsynaptic potential (EPSP). EPSPs are changes in the membrane potential of a postsynaptic neuron that make it more likely to fire an action potential. This typically involves depolarization, where the inside of the neuron becomes less negative.
Step 2: Analyze the options provided. For an EPSP to occur, ions that cause depolarization must flow into the neuron. Sodium ions (Na\(^+\)) are commonly involved in depolarization because their influx makes the membrane potential less negative.
Step 3: Evaluate the first option: 'Inhibition of voltage-gated Ca\(^{2+}\) channels at the presynaptic terminal.' This does not directly cause depolarization in the postsynaptic neuron, so it is not an EPSP.
Step 4: Evaluate the second option: 'Opening of ligand-gated Cl\(^-\) channels causing membrane hyperpolarization.' Hyperpolarization makes the membrane potential more negative, which is inhibitory rather than excitatory, so this is not an EPSP.
Step 5: Evaluate the fourth option: 'Opening of ligand-gated Na\(^+\) channels causing membrane depolarization.' The influx of Na\(^+\) ions reduces the negativity of the membrane potential, leading to depolarization, which is characteristic of an EPSP. This is the correct answer.
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