Nerve Impulses & Electroencephalography - Vocabulary Flashcards

Vocabulary flashcards covering key terms and concepts from nerve impulses and EEG topics.

Threshold potential

The membrane voltage (-55 mV or more positive) required to trigger an action potential.

Na+ voltage-gated channels

Ion channels in axons that open at threshold, allowing Na+ influx to initiate the action potential.

All-or-none principle

An action potential either occurs fully or not at all once threshold is reached.

Action potential

A rapid, transient electrical event that travels along the axon, driven by Na+ and K+ channel activity.

Resting membrane potential (RMP)

Baseline membrane voltage, typically about -70 mV, maintained by ion gradients and pumps.

Na+/K+ ATPase pump

Active transporter that maintains RMP by exchanging Na+ and K+ across the plasma membrane.

Depolarization

Phase during which the membrane potential becomes less negative due to Na+ entry.

Repolarization

Phase during which the membrane returns toward negative by K+ efflux.

Hyperpolarization

Temporary membrane hyperpolarization below the resting potential after an AP.

Saltatory conduction

Fast AP propagation that jumps between Nodes of Ranvier in myelinated axons.

Nodes of Ranvier

Gaps in the myelin sheath where Na+ voltage-gated channels are concentrated.

Myelin

Insulating sheath around axons that increases conduction velocity.

Schwann cells

PNS glial cells that form myelin around peripheral axons.

Oligodendrocytes

CNS glial cells that form myelin around central axons.

Conduction velocity

Speed at which an action potential travels along an axon; increases with diameter and myelination.

Large axon diameter

A larger diameter reduces internal resistance, increasing conduction velocity.

Multiple sclerosis (MS)

Autoimmune demyelinating disease that slows conduction and causes symptoms.

EPSP

Excitatory postsynaptic potential; depolarizing, graded postsynaptic response.

IPSP

Inhibitory postsynaptic potential; hyperpolarizing, graded postsynaptic response.

Synaptic summation

Addition of EPSPs and IPSPs at the postsynaptic membrane to reach threshold.

Neurotoxins

Substances that disrupt nerve signaling; examples include saxitoxin, tetrodotoxin, apamin, botulinum toxin, curare, batrachotoxin.

Saxitoxin

Toxin from red tide that blocks Na+ voltage-gated channels, inhibiting APs.

Tetrodotoxin

Toxin from pufferfish that blocks Na+ voltage-gated channels, inhibiting APs.

Compound action potential

The summed electrical response recorded from a whole nerve, reflecting many axons firing.

Electroencephalography (EEG)

Recording of brain electrical activity via scalp electrodes for diagnosis and brain death assessment.

Bipolar EEG recording

EEG method using two active electrodes to measure voltage differences, with a ground/reference electrode.

Brain waves

Rhythmic electrical activity of the brain measured by EEG, classified by frequency and amplitude.

Alpha waves

Waves 8–13 Hz with 20–200 μV amplitude; occur in relaxed wakefulness with eyes closed; desynchronized by eyes opening (alpha block).

Beta waves

Waves 13–30 Hz with 5–10 μV amplitude; linked to processing, attention, and REM sleep.

Delta waves

Waves 1–5 Hz; dominant in deep sleep (stages 3–4) and in infants; abnormal when awake.

Theta waves

Waves 4–8 Hz; seen in stage 1 sleep and in children; associated with hippocampal activity and stress.

Alpha block (desynchronization)

Suppression of alpha activity when eyes open or mental task is performed; amplitude decreases, frequency increases.

REM sleep

Rapid-eye-movement sleep with brainstem signaling, cholinergic activity, dreaming, and REM atonia.

Occipital alpha rhythm

Peak alpha activity often greatest in occipital region during relaxed wakefulness.

Acetylcholine (ACh)

Neurotransmitter; binds nicotinic and muscarinic receptors; excitatory effects at various synapses.

Norepinephrine (NE)

Neurotransmitter of the aminergic system; involved in arousal and attention.

GABA

Gamma-aminobutyric acid; the main inhibitory neurotransmitter in the CNS.

Nicotinic receptor

Ionotropic ACh receptor; ligand-gated channel that typically depolarizes the postsynaptic cell.

Muscarinic receptor

Metabotropic ACh receptor; G-protein coupled; effects can be excitatory or inhibitory.

Activation mechanisms

Ways to activate neurons: mechanical stimulation, light, or chemical neurotransmitters.

Multipolar neuron

Neuron with multiple processes (dendrites) emanating from the cell body; common in motor pathways.

Axon hillock

Region at the junction of the cell body and axon where action potentials are initiated.

Ground/reference electrode

Third electrode in EEG setups used to reference or ground the recording.