Summary of Action Potential and Sodium-Potassium Pump

Sodium-Potassium Pump

• Key in restoring resting state after action potential.

• Pumps out 3 Na⁺ ions and brings in 2 K⁺ ions.

• Operates during and after action potential, specifically during refractory periods.

Action Potential Cycle

• Involves depolarization (Na⁺ in) followed by repolarization (K⁺ out).

• Cannot trigger a new potential until after refractory period.

• Follows a curve back to resting state—no reverse action.

Postsynaptic Potentials

• Types: excitatory (EPSP) and inhibitory (IPSP).

• EPSPs can sum to trigger action potent ial at axon hillock, while IPSPs stabilize below threshold.

• Spatial summation: combining potentials from different locations.

• Temporal summation: combining potentials that are time-wise close together.

Myelin Sheath and Action Potential

• Myelin sheath crucial for fast conduction. Degeneration (e.g., multiple sclerosis) slows down action potentials.