Action potential propagation in a skeletal muscle fiber ceases when acetylcholine is removed from the synaptic cleft. Which of t
he following mechanisms ensures a rapid and efficient removal of acetylcholine?a) Acetylcholine is degraded by acetylcholinesterase.b) Acetylcholine is transported back into the axon terminal by a reuptake mechanism.c) Acetylcholine is transported into the postsynaptic neuron by receptor-mediated endocytosis.d) Acetylcholine diffuses away from the cleft.
a) Acetylcholine is degraded by acetylcholinesterase.
Explanation:
After it binds for its receptor on the plasma membrane of the postsynaptic cell, acetylcholine must be removed in order to prevent repeated stimulation. Acetylcholinesterase is enzyme for the inactivation of acetylcholine, present at all cholinergic synapses. This enzyme hydrolyses acetylcholine and breaks it to the acetate and choline. Choline can be reused for the synthesis of the new acetylcholine molecule so it is taken back into the presynaptic cell.
