What is the function of the neuromuscular junction?
A.
To connect muscle fibers to motor neurons
B.
To bind acetylcholine to nAChRs
C.
To depolarize the muscle cell membrane.
D.
To activate voltage-gated sodium channels on the muscle membrane .
The correct answer is A. To connect muscle fibers to motor neurons.
Explanation:
The neuromuscular junction (NMJ) is the synapse or connection between a motor neuron and a skeletal muscle fiber. Its primary function is to transmit signals from the motor neuron to the muscle fiber, leading to muscle contraction. Here’s how it works:
- A. To connect muscle fibers to motor neurons:
This is the most accurate description of the primary function of the neuromuscular junction. The NMJ is the site where the motor neuron’s axon terminal meets the muscle fiber’s membrane, facilitating the transmission of signals. - B. To bind acetylcholine to nAChRs:
While it is true that acetylcholine (ACh) binds to nicotinic acetylcholine receptors (nAChRs) at the NMJ, this is a specific step in the process, not the overall function of the NMJ. - C. To depolarize the muscle cell membrane:
Depolarization of the muscle membrane is a consequence of the signal transmission at the NMJ, but it is not the primary function of the NMJ itself. - D. To activate voltage-gated sodium channels on the muscle membrane:
Activation of these channels occurs as part of the muscle fiber’s response to the signal transmitted at the NMJ, but again, this is not the primary function of the NMJ.
Therefore, the correct answer, describing the NMJ’s primary role, is A. To connect muscle fibers to motor neurons.