Action Potentials and Nerve Impulses

These flashcards cover key concepts related to action potentials, including their phases, mechanisms, and the physiological processes involved.

Threshold

The membrane potential that must be reached for an action potential to occur, typically around -55 mV.

Positive Feedback

A mechanism where an initial small change is amplified into a larger change, as seen during depolarization.

Depolarization

The process of reducing the membrane potential from -70 mV to +30 mV, primarily due to sodium influx.

Repolarization

The phase where the membrane potential returns to -70 mV, involving potassium efflux.

Hyperpolarization

A phase following repolarization where the cell becomes more negative than its resting potential due to continued efflux of potassium ions.

Na+/K+ Pump

A cellular pump that restores the original distribution of sodium and potassium ions across the membrane after an action potential.

Nerve Impulse

The traveling voltage change along an axon, sarcolemma, or T-tubules.

Absolute Refractory Period

The time after an action potential during which a neuron cannot fire another action potential, regardless of stimulus strength.

Relative Refractory Period

The time following an action potential during which a neuron can only fire if the stimulus is stronger than usual.

Voltage Gated Sodium Channels

Channels that open in response to membrane depolarization, allowing Na+ ions to flow into the cell.

Voltage Gated Potassium Channels

Channels that open in response to depolarization, allowing K+ ions to flow out of the cell.