Neuronal Electrical Signaling & Membrane Physiology – Core Vocabulary

These vocabulary flashcards cover the fundamental terms involved in neuronal electrical activity, including membrane potentials, ion channels, graded and action potentials, and their physiological significance.

Neuron

A nerve cell specialized for receiving, processing, and transmitting electrical signals.

Soma (Cell Body)

The central region of a neuron that houses the nucleus and integrates incoming signals.

Dendrite

Short, branching neuronal processes that receive graded potentials from other cells.

Axon

A long neuronal process that carries action potentials from the axon hillock to axon terminals.

Axon Hillock

The trigger zone at the base of the axon where graded potentials sum and, if threshold is reached, initiate an action potential.

Graded Potential

A variable-strength electrical change in dendrites or soma that can be depolarizing (yes) or hyperpolarizing (no).

Action Potential

An all-or-none electrical impulse that propagates unidirectionally down the axon once threshold is achieved.

Threshold

The membrane potential level that must be reached at the axon hillock to trigger an action potential.

Excitable Cell

A cell (e.g., neuron or muscle) capable of generating action and graded potentials.

Resting Membrane Potential

The baseline transmembrane voltage of a neuron (~–70 mV) resulting from unequal ion distributions.

Transmembrane Potential

The voltage difference between the inside and outside of a cell membrane.

Leak Channel

An ion channel that opens randomly, permitting passive ion diffusion (e.g., Na⁺ or K⁺).

Ligand-Gated Channel

An ion channel that opens when a specific chemical (ligand) binds to it.

Mechanical-Gated Channel

An ion channel that opens in response to physical deformation of the membrane (touch, pressure, vibration).

Voltage-Gated Channel

An ion channel that opens when the membrane potential reaches a specific voltage.

Sodium–Potassium Pump (Na⁺/K⁺ ATPase)

An active transport protein that moves 3 Na⁺ out and 2 K⁺ into the cell using ATP, maintaining ion gradients.

Ion Gradient

Unequal concentration of a specific ion across a membrane, driving diffusion when channels open.

Electrical Gradient

The difference in overall charge across a membrane (more positive outside, more negative inside in neurons).

Sodium Gradient

Higher concentration of Na⁺ outside the neuron than inside at rest.

Potassium Gradient

Higher concentration of K⁺ inside the neuron than outside at rest.

Depolarization

A shift toward 0 mV (less negative) caused typically by Na⁺ entering the cell; increases chance of firing.

Hyperpolarization

A shift to a more negative membrane potential, often produced by K⁺ leaving the cell; decreases excitability.

Summation

The additive effect of multiple graded potentials occurring close together in time or space.

Synaptic Bulb (Terminal)

The swollen end of an axon that releases neurotransmitters to communicate with the next cell.

Battery Analogy

Comparison of the resting membrane potential to separated positive and negative charges in a battery, providing stored energy.

Trigger Zone

Functional term for the axon hillock region where action potentials originate.

All-or-None Principle

Rule stating that an action potential either occurs fully (once threshold is crossed) or not at all.

Long-Distance Signaling

Communication via action potentials that can travel the entire length of very long axons.

Short-Distance Signaling

Communication via graded potentials confined to dendrites and soma.