Final answer:
The correct sequence of events during transmission at the cholinergic synapse is the arrival of an action potential, the opening of Ca²⁺ channels and influx of calcium, the release of acetylcholine, the binding of acetylcholine to postsynaptic receptors, and the activation of ion channels on the postsynaptic membrane.
Step-by-step explanation:
The process of signal transmission at a cholinergic synapse is a series of events that begins when an action potential arrives at the presynaptic membrane, causing depolarization. This depolarization causes voltage-gated Ca²⁺ channels to open, allowing calcium ions to flow into the axon terminal. The influx of calcium ions triggers the release of neurotransmitter molecules, acetylcholine (ACh), from their vesicles into the synaptic cleft through exocytosis.
The acetylcholine then diffuses across the synaptic cleft and binds to receptors on the postsynaptic membrane, activating chemically regulated ion channels. This binding causes the channels to open, allowing ions to flow in and out of the postsynaptic cell, which can then lead to depolarization or a change in the membrane potential. The correct order for these events is B) 3, 2, 4, 5, 1:
- An action potential depolarizes the axon terminal at the presynaptic membrane.
- Calcium ions enter the axon terminal.
- Acetylcholine is released from storage vesicles by exocytosis.
- Acetylcholine binds to receptors on the postsynaptic membrane.
- Chemically regulated ion channels on the postsynaptic membrane are activated.