19. Which of the following statements are accurate?

A. At rest, excitable cells (e. g. neurons) have a negative charge.

B. Once a depolarization reaches threshold, an action potential will most likely occur, however, a strong repolarization or hyperpolarization event could prevent the action potential.

C. Repolarization of a neuron results from sodium diffusing out of the cell.

D. To reach threshold, cells at rest must hyperpolarize.

E. Sodium diffusing out of a neuron will cause depolarization

Options A and B are accurate

Explanation:

Neurons at rest usually have a negative charge meaning they have negative concentration gradient most of the time wherein there are more positively charged ions outside than inside the cell. Depolarization lets positively charged sodium ions flow into the negatively charged axon, depolarizing the surrounding axon. this goes over the equilibrium reaching threshold and becomes very positively charged allowing action potential to pass through.

Repolarization occurs when the cell is brought back to its resting potential by inactivating the gates of the sodium channels making them close preventing their inflow and allowing for the exit of the potassium ions.

the sphincter muscles at the end of the digestive tract is the anus.

i think its control and coordinate because im pretty sure thats what tissue does and the joints are what control movement and then your skeletal/ bones provides portection. hope that .