Which of the following is the most direct result of depolarizing the presynaptic membrane of an axon terminal?
a. Voltage-gated calcium channels in the membrane open
b. Synaptic vesicles fuse with the membrane
c. Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft
d. An EPSP or IPSP is generated in the postsynaptic cell

검증된 단계별 안내

Understand the context: Depolarization of the presynaptic membrane is a crucial step in the process of synaptic transmission, which involves the release of neurotransmitters from the presynaptic neuron to the postsynaptic neuron.

Identify the sequence of events: When an action potential reaches the axon terminal, it causes depolarization of the presynaptic membrane.

Recognize the role of ion channels: Depolarization of the presynaptic membrane leads to the opening of specific ion channels. In this case, focus on voltage-gated calcium channels, which are sensitive to changes in membrane potential.

Link the opening of channels to subsequent events: The opening of voltage-gated calcium channels allows calcium ions to enter the presynaptic neuron, which is a critical step for the fusion of synaptic vesicles with the presynaptic membrane.

Conclude the direct result: The most direct result of depolarizing the presynaptic membrane is the opening of voltage-gated calcium channels, which is the initial trigger for the subsequent steps in neurotransmitter release.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Depolarization of the Presynaptic Membrane

Depolarization refers to the reduction in membrane potential, making the inside of the neuron less negative compared to the outside. In the context of an axon terminal, depolarization is crucial as it triggers the opening of voltage-gated ion channels, which is a key step in neurotransmitter release during synaptic transmission.

Voltage-Gated Calcium Channels

Voltage-gated calcium channels are specialized proteins in the presynaptic membrane that open in response to depolarization. When these channels open, calcium ions flow into the neuron, which is essential for the fusion of synaptic vesicles with the presynaptic membrane, leading to neurotransmitter release into the synaptic cleft.

Synaptic Vesicle Fusion

Synaptic vesicle fusion is the process by which vesicles containing neurotransmitters merge with the presynaptic membrane. This fusion is triggered by the influx of calcium ions following the opening of voltage-gated calcium channels. The release of neurotransmitters into the synaptic cleft is a critical step in transmitting signals to the postsynaptic neuron.