The following are the steps involved in transmission at a cholinergic synapse.
1) Chemically gated sodium channels on the postsynaptic membrane are activated.
2) Calcium ions enter the synaptic knob.
3) Acetylcholinesterase hydrolyzes acetylcholine.
4) An action potential depolarizes the synaptic knob at the presynaptic membrane.
5) The synaptic knob reabsorbs choline.
6) Acetylcholine is released from storage vesicles by exocytosis.
7) Acetylcholine binds to receptors on the postsynaptic membrane.
8) Calcium ions are removed from the cytoplasm of the synaptic knob.
The correct sequence for these events is
A) 4, 2, 6, 7, 8, 5, 3, 1.
B) 4, 2, 6, 7, 1, 8, 3, 5.
C) 2, 4, 6, 7, 1, 8, 3, 5.
D) 2, 5, 4, 6, 7, 1, 8, 3.
E) 6, 4, 2, 7, 1, 8, 3, 5.

Question

Quizplus · Accepted Answer

The correct sequence of events in transmission at a cholinergic synapse starts with an action potential depolarizing the synaptic knob at the presynaptic membrane (4), followed by calcium ions entering the synaptic knob (2). This triggers the release of acetylcholine from storage vesicles by exocytosis (6), which then binds to receptors on the postsynaptic membrane (7). This binding activates chemically gated sodium channels, causing depolarization of the postsynaptic membrane (1). Acetylcholinesterase hydrolyzes acetylcholine (3) to prevent continuous stimulation of the postsynaptic neuron. Calcium ions are then removed from the cytoplasm of the synaptic knob (8), and any remaining acetylcholine is reabsorbed by the synaptic knob for reuse (5). Therefore, the correct sequence of events is 4, 2, 6, 7, 1, 8, 3, 5. This sequence of events is described in choice B.

The Following Are the Steps Involved in Transmission at a Cholinergic