Which of the following statements regarding the motor end plate of a skeletal muscle fiber is TRUE? A) Muscarinic receptors in the end plate are activated by binding to acetylcholine. B) Temporal summation of multiple end plate potentials is required in order to trigger an action potential in the muscle-fiber membrane. C) Acetylcholinesterase in the end plate membrane catalyzes the breakdown of acetylcholine. D) Sympathetic nerve fibers terminate on skeletal muscle fibers at the motor end plate. E) The motor end plate under the axon terminal contains a large number of voltage-gated Na⁺ channels.

Question

Quizplus · Accepted Answer

Acetylcholinesterase, an enzyme in the end plate membrane, breaks down acetylcholine in the synaptic cleft, terminating the signal transmission between the motor neuron and muscle fiber. Muscarinic receptors are found in other parts of the body and not in the motor end plate. Temporal summation occurs at the level of the muscle cell membrane and not specifically in the motor end plate. Sympathetic nerve fibers do not terminate on the motor end plate, but instead release norepinephrine to modulate muscle contraction. Voltage-gated Na+ and K+ channels are found in the muscle cell membrane but not specifically in the motor end plate.

Which of the Following Statements Regarding the Motor End Plate