Select all that are true regarding a resting muscle fiber.

Out of the following given choices;

1) There is a charge difference across the sarcolemma.

2) Sodium-potassium pumps are active.

3) Calcium is stored in the sarcoplasm.

4) ACh receptors are open.

The answer is 1, 3 and 4. When a muscle is at rest, the Ca2 + ions are still sequestered in the sarcoplasm until an impulse induces depolarization. ACh receptors are also not bound by acetylcholine which is the primary receptor-neurotransmitter in muscle for motor nerve-muscle communication that controls muscle contraction.