Action potential

Definition

An action potential is a rapid, temporary change in the electrical membrane potential of a cell. It is essential for the conduction of electrical impulses in cardiac and nerve cells.

5 Must Know Facts For Your Next Test

1. Action potentials are initiated when the membrane potential reaches a threshold level due to depolarization.
2. They involve phases like depolarization, repolarization, and sometimes hyperpolarization.
3. In cardiac cells, action potentials ensure coordinated contraction of the heart muscle.
4. Sodium (Na+) and potassium (K+) ions play crucial roles in generating action potentials.
5. The refractory period during an action potential prevents immediate re-excitation of the cell.

Review Questions

• What ions are primarily involved in generating action potentials?
• How does an action potential contribute to heart muscle contraction?
• What is the significance of the refractory period in an action potential?

Related terms

Depolarization: A decrease in membrane potential that makes the inside of the cell less negative compared to the outside.

Refractory Period: A period during which a neuron or muscle cell is incapable of repeating an action potential.

Sodium-Potassium Pump: A cellular mechanism that uses ATP to transport Na+ out and K+ into the cell, helping maintain membrane potential.