Neural Signaling: Ion Gradients and Ion Channels (Vocabulary)

Vocabulary flashcards covering key concepts from the neural signaling lecture notes.

Neuron signaling

The process by which neurons convey information through electrical and chemical changes within and between cells.

Ions

Atoms that have gained or lost electrons, producing charged particles essential for electrical signaling.

Cation

A positively charged ion (e.g., Na+, K+, Ca2+).

Anion

A negatively charged ion (e.g., Cl−) or large negatively charged intracellular proteins.

Sodium (Na+)

A major extracellular cation that tends to move into the cell via gradients and channels.

Potassium (K+)

A major intracellular cation that tends to move out of the cell via gradients and channels.

Chloride (Cl−)

An anion that is high outside the cell and moves inward through channels under gradients.

Calcium (Ca2+)

An extracellularly high cation that moves into the cell through channels when permitted.

Anions (intracellular proteins)

Large negatively charged proteins inside the cell contributing to a negative internal environment.

Resting membrane potential (Vm)

The baseline electrical potential across the neuron’s membrane due to ion distribution and membrane properties.

Membrane potential

Electrical potential difference across the cell membrane created by the separation of charges.

Resting baseline

The typical distribution of ions when the neuron is not actively signaling, forming the resting state.

Electrical potential across the membrane

The voltage difference created by charge separation across the membrane.

Concentration gradient

Driving force where ions move from regions of high concentration to low concentration.

Electrical gradient

Driving force where charges attract or repel, influencing ion movement.

Electrochemical gradient

Combined influence of chemical (concentration) and electrical gradients on ion movement.

Driving force

Energy that moves ions across the membrane, provided by gradients or voltage.

Equilibrium (gradient)

A state where ion concentrations become equal on both sides, with no net movement.

Ion channels

Protein pores in the cell membrane that allow ions to pass through.

Passive (leak) channels

Channels that are always open, permitting ion flow according to gradients.

Ligand-gated channel

Ion channel opened by binding of a chemical messenger (ligand).

Voltage-gated channel

Ion channel opened by a change in membrane voltage; gate opened by voltage changes.

Mechanically gated channel

Ion channel opened by mechanical force or membrane deformation.

Gating

Process of opening or closing ion channels in response to stimuli or signals.

Ion pump

Active transporter that uses energy (ATP) to move ions against their gradient.

Sodium-potassium pump (Na+/K+ pump)

Active transporter that moves Na+ out and K+ in to maintain resting conditions.

Calcium pump

Active transporter that moves Ca2+ out or sequesters it to regulate intracellular calcium.

Ion transporter

A transporter that uses energy to move ions, often against their gradient (active transport).

Passive vs gated channels

Passive channels are always open; gated channels open/close in response to ligands, voltage, or mechanical stimuli.

Resting state distribution

The specific ion distribution that establishes the resting membrane potential from which signals arise.

Membrane potential as charge separation

Vm arises from the separation of charges across the thin cell membrane and represents potential energy.

Current

Flow of electric charges (ions) through a pathway, measured as coulombs per second in biology.

Coulomb

Unit of electric charge; used to quantify current as charge flow per unit time.

Ohm

Unit of electrical resistance, describing how strongly a pathway resists current.

Voltage

Electrical pressure that drives ion movement, creating potential difference across the membrane.

Resistance

Opposition to current flow within a pathway, influenced by the membrane and channels.

Ohm’s law (concept)

Relationship among voltage (V), current (I), and resistance (R): V = IR; describes how voltage drives current through resistance.

Ion channels as pathways

Proteins that form bridges in the membrane, enabling ions to move across the otherwise impermeable bilayer.

Localization of channels

Passive channels are widespread; ligand-gated channels are typically in dendrites; voltage-gated channels are in the axon hillock, axon, and presynaptic terminals.

Membrane potential maintenance

Na+/K+ pump and leak channels help maintain the resting membrane potential.

Electrochemical gradient in signaling

Ion movement is governed by both chemical and electrical forces acting together.