Question

Which of the following is/are mechanism(s) to end neural transmission at the neuromuscular junction?

Select all the correct answers.
1.ACh is taken up by the axon terminal via endocytosis.
2.ACh diffuses away from the synaptic cleft.
3.ACh binds to ACh receptors.
4.ACh is broken down into acetic acid and choline by the enzyme acetylcholinesterase (AChE).

Answer 1

The mechanisms to end neural transmission at the neuromuscular junction include endocytosis of ACh and its breakdown by acetylcholinesterase (AChE).

Step-by-step explanation:

Neurotransmission at the neuromuscular junction can be terminated through multiple mechanisms:

1. ACh is taken up by the axon terminal via endocytosis. After ACh is released into the synaptic cleft, it can be rapidly taken up by the axon terminal through endocytosis, preventing further binding to ACh receptors.
2. ACh is broken down into acetic acid and choline by the enzyme acetylcholinesterase (AChE). AChE, which is present in the synaptic cleft, breaks down ACh into acetic acid and choline, preventing prolonged binding to ACh receptors.

Therefore, options 1 and 4 are the correct mechanisms to end neural transmission at the neuromuscular junction.

Answer 2

Neural transmission at the NMJ is ended by ACh diffusing away from the synaptic cleft and by ACh being broken down by acetylcholinesterase (AChE).

Step-by-step explanation:

The mechanisms to end neural transmission at the neuromuscular junction (NMJ) include two main actions:

• Acetylcholine (ACh) diffusion away from the synaptic cleft.
• ACh is broken down into acetic acid and choline by the enzyme acetylcholinesterase (AChE).

The first mechanism, where ACh diffuses away from the synaptic cleft, prevents it from continually stimulating the post-synaptic neuron. The second, more direct and efficient, mechanism involves the enzyme AChE, which resides in the synaptic cleft and breaks down ACh so that it does not remain bound to the ACh receptors on the muscle cells, preventing unwanted, prolonged muscle contraction.

It's important to note that the other listed options are not mechanisms for ending the transmission. ACh binding to ACh receptors (Option 3) is actually part of the transmission process, and ACh is not taken up by the axon terminal via endocytosis (Option 1) to end transmission; instead, it's broken down in the synaptic cleft.