During an action potential, the phase where ___________ moves into the cell results in depolarization while the phase where ______________ exits the cell results in repolarization. 

What is the role of the calcium ion in the signaling of an action potential at the neuromuscular junction?

True or false: if false, choose the answer that best corrects the statement:

The motor neuron is in contact with the sarcolemma in order to efficiently pass the electrical signal to the muscle fiber.

Voltage gated channels respond to the depolarization of an action potential by releasing Ca$^2$$^+$. Where are these channels located?

In a skeletal muscle fiber, which structure would you expect to have the greatest total surface area?

Which part of the cross-bridge cycle is called the power stroke?

What would happen if a muscle completely ran out of ATP during a muscle contraction.