LECTURE 4

Question 1

Why are nerves and muscle fibers called “excitable cells”?

Answer 1

They conduct currents

Question 2

What are the relative differences in concentrations of sodium (Na) and potassium (K) between the inside and outside of the cell?

Answer 2

There is more Na outside the cell and there is more potassium inside the cell and they both have high concentrations in those places

Question 3

What is an electrically gated channel?

Answer 3

Protein which allows sodium to enter and the permeability varies with electrical potential (opens/closes) depending on electrical potential)

Question 4

What is the difference between depolarization and propagation?

Answer 4

Depolarization: change in potential of channel (inside becomes more positive)
Propagation: movement of depolarization wave along surface of the muscle

Question 5

Which ion floods into the excitable cells during the action potential?

Answer 5

Sodium (Na)