Electrical Properties of Neurons — Vocabulary Flashcards

Vocabulary flashcards covering key terms related to the electrical activity of neurons, synaptic transmission, and conduction.

Resting potential

Baseline membrane potential when a neuron is not stimulated, typically negative inside (-50 to -80 mV) due to ion gradients.

Ion gradient

Unequal distribution of ions across the membrane that contributes to the resting potential.

Ion channels

Proteins spanning the membrane that allow ions to pass; include selective, gated, and constitutively open variants.

Gated channels

Ion channels that open or close in response to specific signals or events.

Diffusion

Movement of particles from high to low concentration until uniform in solution.

Electrostatic force

Force driving ion movement based on charge; part of what moves ions across membranes.

Voltage

A measure of the potential for the electrostatic force to move a charged particle across a membrane.

Na+/K+ pump

Active transporter that exchanges 3 Na+ out for 2 K+ in, using ATP to maintain ion gradients.

Depolarization

Membrane potential becomes less negative (inside more positive).

Hyperpolarization

Membrane potential becomes more negative (inside more negative).

Threshold

Membrane potential at which an action potential is triggered (around -40 mV).

Action potential

All-or-none electrical signal that rapidly depolarizes and repolarizes a segment of the axon and propagates along it.

All-or-none

Principle that an action potential occurs fully or not at all; amplitude is constant once threshold is reached.

Refractory period

A short period after an action potential during which voltage-gated Na+ channels can’t reopen, enforcing unidirectional travel.

Axon hillock

Region at the start of the axon where postsynaptic potentials are integrated to reach threshold.

Voltage-gated Na+ channels

Channels that open to allow Na+ influx during depolarization; close near +40 mV.

Voltage-gated K+ channels

Channels that open during repolarization to allow K+ efflux, helping return to resting potential.

Nodes of Ranvier

Gaps in myelin where action potentials are regenerated during saltatory conduction.

Myelin

Insulating sheath around axons produced by glia; speeds conduction of action potentials.

Saltatory conduction

Propagation of an action potential by jumping from node to node in a myelinated axon.

Axon diameter

Thicker axons conduct action potentials faster.

Multiple sclerosis

Disease in which demyelination disrupts action potential conduction.

Local anesthetics (-caine)

Drugs that block voltage-gated Na+ channels to dull sensation (e.g., procaine, lidocaine, cocaine).

Tetrodotoxin (TTX)

Potent toxin that blocks voltage-gated Na+ channels, preventing action potentials.

Ca2+ channels

Voltage-gated channels that open in the axon terminal to allow Ca2+ influx, triggering neurotransmitter release.

Calcium sensor

Calcium-binding protein that detects Ca2+ and triggers vesicle docking/fusion for neurotransmitter release.

Vesicle docking

Process by which synaptic vesicles attach to the presynaptic membrane in preparation for release.

Neurotransmitter release

Ca2+-triggered exocytosis of neurotransmitter into the synaptic cleft.

Synaptic cleft

Gap between presynaptic and postsynaptic membranes where neurotransmitters diffuse.

Neurotransmitter

Chemical signal released by a neuron to influence another neuron or target cell.

Ionotropic receptors

Postsynaptic receptors that form ion channels and open when a neurotransmitter binds, producing EPSP or IPSP.

Nicotinic acetylcholine receptor

A five-subunit ionotropic receptor; opens Na+/Ca2+ channels when acetylcholine (or nicotine) binds, causing depolarization.

Acetylcholine

A neurotransmitter involved in neuromuscular and several central nervous system pathways.

EPSP (Excitatory postsynaptic potential)

Depolarizing postsynaptic potential produced by ion channels that let positive ions in.

IPSP (Inhibitory postsynaptic potential)

Hyperpolarizing postsynaptic potential produced by ion channels that let negative ions in.

Summation

Algebraic integration of multiple PSPs; determines whether the neuron reaches threshold.

Temporal summation

Accumulation of PSPs over time at a single synapse.

Spatial summation

Accumulation of PSPs across multiple synapses at different locations.

Graded potentials

PSPs that vary in size and duration depending on input strength and neurotransmitter amount.