Introduction to Brain and Behavior: Neurons and Electrical Signals (Vocabulary)

Vocabulary flashcards covering key terms related to neuronal signaling, membranes, and synaptic transmission from Chapters 4.1–4.3.

Neon

[Note: This card is intentionally ignored; see next card for a proper term.]

Neuron

A nerve cell that transmits information via electrical impulses along its axon and communicates at synapses.

Resting potential

The steady membrane potential of a neuron at rest, typically about -70 mV, maintained by ion distributions and selective permeability.

Action potential

A brief, large reversal in membrane potential that travels along the axon; lasts about 1 ms and is initiated when the membrane potential reaches threshold.

Threshold

The membrane potential, about -50 mV, at which an action potential is triggered.

Depolarization

A change in membrane potential toward a more positive value due to Na+ influx.

Hyperpolarization

A change in membrane potential toward a more negative value, often due to K+ efflux or Cl− influx.

Ion channels

Protein channels in the cell membrane that open or close to regulate ion flow; include voltage-gated and ligand-gated channels.

Ligand-gated ion channels

Channels that open when a neurotransmitter binds to a receptor at a synapse.

Voltage-gated ion channels

Channels that open or close in response to changes in membrane voltage; crucial for action potentials.

Sodium channels (Na+ channels)

Voltage-gated channels that open to allow Na+ influx during depolarization.

Potassium channels (K+ channels)

Voltage-gated channels that open to allow K+ efflux during repolarization.

Sodium–potassium pump (Na+/K+ pump)

Active transporter that maintains Na+ and K+ gradients; moves 3 Na+ out for every 2 K+ in.

Concentration gradient

The difference in ion concentration across the membrane that drives diffusion.

Electrical gradient

The difference in electrical charge across the membrane that drives ion movement.

Diffusion

Movement of ions from areas of high concentration to low concentration toward equilibrium.

Node of Ranvier

Gaps in the myelin sheath rich in voltage-gated channels; enable saltatory conduction.

Myelin sheath

Insulating layer around axons formed by glial cells; speeds neural conduction.

Saltatory conduction

Propagation of an action potential from node to node along a myelinated axon.

Oligodendrocytes

CNS glial cells that form the myelin sheath around axons.

Schwann cells

PNS glial cells that form the myelin sheath around axons.

Axon hillock

Junction of soma and axon; rich in voltage-gated channels; where EPSPs/IPSPs are integrated and APs are initiated.

Excitatory postsynaptic potential (EPSP)

A brief depolarization that increases the probability of an action potential.

Inhibitory postsynaptic potential (IPSP)

A brief hyperpolarization that decreases the probability of an action potential.

Synapse

Junction where neurotransmitter is released from the presynaptic neuron and binds to receptors on the postsynaptic neuron.

Neurotransmitter

Chemical messenger released at the synapse that binds to postsynaptic receptors and can open ligand-gated channels.

Temporal summation

Repeated inputs from the same neuron that summate over time to influence firing.

Spatial summation

Inputs from multiple neurons at different locations that summate to influence firing.

Graded potential

A synaptic potential (EPSP/IPSP) that varies in size and decays with time and distance.

All-or-none law

Once initiated, an action potential maintains its size and shape along the axon.

Absolute refractory period

The period after an AP during which a new AP cannot be elicited.

Relative refractory period

The period after an AP when a stronger-than-normal stimulus is needed to elicit another AP.