Video Transcript
The diagram provided shows a basic
outline of a neuromuscular junction. What is the role of acetylcholine
at a neuromuscular junction? (A) To act as a biological
catalyst. (B) To open the voltage-gated
calcium channels on the presynaptic neuron. (C) To act as a chemical
neurotransmitter. Or (D) to move tropomyosin away
from the myosin-binding sites on actin filaments.
To answer this question, let’s
first look at what a neuromuscular junction is and the processes it’s involved
in. A neuromuscular junction is a
synaptic connection between the axon of a motor neuron and a muscle fiber. This connection is important as it
allows the motor neuron to transmit a signal to the muscle fiber. As the diagram shows, there is a
gap between the motor neuron and the muscle fiber. This gap is called the synaptic
cleft.
Neurotransmitters are chemicals
made by and stored in the neuron and are used to pass information across the
synaptic cleft to a target cell, which can be a different neuron, a gland cell, or a
muscle cell in the case of a neuromuscular junction. In skeletal muscle, the
neurotransmitter that is used at neuromuscular junctions is called
acetylcholine.
Now that we know this information,
we can answer the question correctly. The role of acetylcholine at a
neuromuscular junction is (C), to act as a chemical neurotransmitter.
