View the animation below, then complete the quiz to test your knowledge of the concept.

1	An action potential arriving at the presynaptic terminal causes...
	A)	sodium ions to diffuse into the cell.
	B)	sodium ions to diffuse out of the cell.
	C)	calcium ions to diffuse into the cell.
	D)	acetylcholine to diffuse into the cell.
	E)	ligand-gated sodium channels to open.
2	In the neuromuscular junction, acetylcholine...
	A)	diffuses across the synaptic cleft and binds to acetylcholine receptors on the postsynaptic muscle fiber.
	B)	is actively transported across the synaptic cleft and binds to acetylcholine receptors on the postsynaptic muscle fiber.
	C)	diffuses across the synaptic cleft and causes calcium ions to diffuse into the postsynaptic muscle fiber.
	D)	diffuses across the synaptic cleft and causes sodium ions to diffuse out of the postsynaptic muscle fiber.
	E)	is actively transported across the synaptic cleft and causes calcium ions to diffuse into the postsynaptic muscle fiber.
3	The neurotransmitter in the neuromuscular junction...
	A)	causes ligand gated calcium channels in the muscle fiber to increase their permeability to calcium, which depolarizes the postsynaptic membrane.
	B)	causes ligand gated sodium channels in the muscle fiber to increase their permeability to sodium, which depolarizes the postsynaptic membrane.
	C)	increases the calcium ion permeability of the presynaptic membrane.
	D)	increases the sodium ion permeability of the presynaptic membrane.
	E)	depolarizes the presynaptic membrane by increasing the permeability of sodium ions.
4	Acetylcholine is broken down into acetic acid and cholinesterase by choline.
	A)	True
	B)	False
5	Once threshold is reached on the postsynaptic membrane, an action potential is generated and propagated over the muscle cell membrane.
	A)	True
	B)	False