Question

1. "Then contraction of the muscle occurs." This sentence follows:

   	A.	depolarization.
   	B.	action potential.
   	C.	nerve impulse.
   	D.	synaptic cleft.
   	E.	neurotransmitter secretion.

Answer 1

"Then contraction of the muscle occurs." This sentence follows: Action potential.

Option (B), Action Potential is correct.

When an action potential moves along the nerves to the muscles, then muscle contraction is caused.

Muscle contraction starts with a signal generated by the nervous system. The signal, an impulse called an action potential, moves through a type of nerve cell called a motor neuron.

When the signal of the nervous system reaches the neuromuscular junction the motor neuron releases a chemical message. A neurotransmitter called acetylcholine, the chemical message binds to the receptors on the outside of the muscle fiber, which begins a chemical reaction inside the muscle.