Lecture on Membrane Potentials and Gated Channels

These flashcards cover essential vocabulary and concepts related to membrane potentials, ion channels, and action potentials discussed in the lecture.

Capacitive Current

The current that changes the charge across the membrane, causing voltage gated channels to begin to open.

Depolarization

The process of reducing the difference in voltage across the membrane, making the inside less negative, eventually reaching about zero.

Gating Current

The current associated with the opening and closing of voltage-gated ion channels.

Threshold

The membrane potential that must be reached to trigger an action potential.

Inactivation Particle

A part of voltage-gated sodium channels that blocks the channel after depolarization to prevent further sodium influx.

Sodium Potassium Pump

A protein that helps maintain resting membrane potential by moving sodium out of and potassium into the cell.

Action Potential

A rapid rise and subsequent fall in voltage or membrane potential across a cellular membrane, primarily due to sodium and potassium ion movements.

Myelination

The process of insulating the axon with myelin sheath, which increases the speed of action potentials.

Voltage-Clamp Technique

An electrophysiological technique that allows control of the membrane potential of a cell while measuring ionic currents.

Length Constant

A measure of how far depolarization can spread along an axon; it depends on the membrane and internal resistance.

Tetrodotoxin

A potent toxin that blocks sodium channels, preventing action potentials.

Calcium Channels

Ion channels that allow calcium ions to enter the cell, affecting various cellular processes including neurotransmitter release.

Outward Current

The movement of positive charges (like potassium ions) out of the cell, which contributes to repolarization.

Hypopolarization

A decrease in the polar difference across the membrane, making it less negative or more positive.

Voltage-Gated Channels

Proteins in the membrane that open or close in response to changes in voltage across the membrane.

Resting Membrane Potential

The baseline potential difference across a cell membrane when the cell is not firing an action potential.

Ion Selectivity

The ability of ion channels to allow certain ions to pass while blocking others.

Propagation of Action Potential

The process by which an action potential is transmitted along the axon, facilitated by the opening of ion channels.

Nodal Regions

Areas along myelinated axons where action potentials are regenerated, rich in voltage-gated sodium channels.

Inward Current

The movement of positive ions (like sodium) into the cell, contributing to depolarization.