Acetylcholine causes an end-plate potential by triggering the
a. opening of calcium channels
b. closing of sodium channels
c. closing of calcium channels
d. closing of chloride channels
e. opening of sodium channels
f. opening of chloride channels

e. Opening of sodium channels

Explanation:

Skeletal muscle fibers are depolarized by the end-plate potential voltage. It is caused by the binding of neurotransmitter acetylcholine to the post synaptic membrane present in the neuromuscular junction. In the absence of a nerve impulse, the end plate membrane has a negative charge inside and a positive charge outside due to uneven distribution of ions. This makes the membrane polarized.

When acetylcholine is released by nerve terminal due to an impulse, it binds to the receptor molecules present on end plate. As a result, sodium channels are opened which leads to influx of sodium ions in the muscle cell. Now the membrane gets slightly depolarized. Slowly acetylcholine is degraded by an enzyme closing the channels and again polarizing the membrane.

the ileocecal valve (also called bauhin valve), which limits the rate of food passage into the cecum and may prevent material from returning to the small intestine.

answer: the answer is d.

explanation: this is because when you exercise you make your muscle produce a certain liquid, that does not evaporate it.   also when you exercise you do not reduce muscle fiber.   and it does not really control your twitch that much.