How is cholinergic transmission primarily terminated?

How is cholinergic transmission primarily terminated?

• A. By reuptake of acetylcholine
• B. By hydrolysis of acetylcholine by acetylcholinesterase
• C. By diffusion away from the synapse
• D. By receptor desensitization

Answer: (B)

Cholinergic transmission is primarily terminated by the hydrolysis of acetylcholine by acetylcholinesterase, which is an enzyme that breaks down acetylcholine into acetate and choline. This rapid degradation of acetylcholine ensures that the signal is transient and that overstimulation of the post-synaptic receptors does not occur. The swift action of acetylcholinesterase is crucial for the proper functioning of the nervous system, especially in environments where rapid signaling is necessary, such as neuromuscular junctions. Once acetylcholine is broken down, the choline can be taken back up into the presynaptic neuron for the synthesis of new acetylcholine, thus completing the cycle of cholinergic transmission. Regarding the other options, reuptake of acetylcholine does not occur in the same way that it does for neurotransmitters like norepinephrine; hydrolysis is the primary mechanism. Although diffusion away from the synapse can occur, it is not the primary method and does not account for the rapid termination needed for cholinergic signaling. Receptor desensitization is a process that affects receptor sensitivity but does not terminate the neurotransmitter action itself.

Cholinergic transmission is primarily terminated by the hydrolysis of acetylcholine by acetylcholinesterase, which is an enzyme that breaks down acetylcholine into acetate and choline. This rapid degradation of acetylcholine ensures that the signal is transient and that overstimulation of the post-synaptic receptors does not occur.

The swift action of acetylcholinesterase is crucial for the proper functioning of the nervous system, especially in environments where rapid signaling is necessary, such as neuromuscular junctions. Once acetylcholine is broken down, the choline can be taken back up into the presynaptic neuron for the synthesis of new acetylcholine, thus completing the cycle of cholinergic transmission.

Regarding the other options, reuptake of acetylcholine does not occur in the same way that it does for neurotransmitters like norepinephrine; hydrolysis is the primary mechanism. Although diffusion away from the synapse can occur, it is not the primary method and does not account for the rapid termination needed for cholinergic signaling. Receptor desensitization is a process that affects receptor sensitivity but does not terminate the neurotransmitter action itself.