Nervous System Overview

Vocabulary flashcards covering essential terms and definitions from the nervous system lecture notes.

Neuron

A specialized nerve cell that carries nerve impulses.

Dendrite

Neuron extension that conducts impulses toward the cell body.

Axon

Neuron extension that conducts impulses away from the cell body.

Fiber (neural)

General term for a dendrite or axon.

Myelin Sheath

Lipid-protein covering that insulates nerve fibers and speeds conduction.

Schwann Cell

Peripheral neuroglial cell that secretes the myelin sheath.

Node of Ranvier

Gap between segments of myelin where the axon membrane is exposed.

Synaptic Knob

Swollen terminal end of an axon containing neurotransmitters.

Central Nervous System (CNS)

Brain and spinal cord; processes information and initiates responses.

Peripheral Nervous System (PNS)

All nervous tissue outside the CNS.

Autonomic Nervous System (ANS)

PNS division controlling involuntary muscles and glands.

Somatic Nervous System

PNS division connecting the CNS to skeletal muscles and sense organs.

Sympathetic Nervous System

ANS branch that prepares the body for emergency "fight or flight" situations.

Parasympathetic Nervous System

ANS branch that promotes relaxed "rest and digest" activities.

Sensory Neuron (Afferent)

Carries impulses from sense organs to the CNS; long dendrite, short axon.

Motor Neuron (Efferent)

Carries impulses from the CNS to muscles or glands; short dendrites, long axon.

Interneuron (Association)

Neuron within the CNS that connects sensory and motor pathways.

Nerve Conduction

Electrochemical change moving along a nerve fiber.

Resting Potential

-60 to -70 mV charge across an unstimulated axon membrane.

Sodium-Potassium Pump

Active transport mechanism maintaining Na⁺ outside and K⁺ inside the axon.

Action Potential

Rapid reversal of membrane polarity when a neuron fires.

Depolarization

Phase when Na⁺ enters the axon, making the inside positive.

Repolarization

Phase when K⁺ exits the axon, restoring negativity inside.

Recovery Phase

Period when the Na⁺/K⁺ pump re-establishes ion distribution using ATP.

Saltatory Conduction

Jumping of impulses between Nodes of Ranvier on myelinated fibers.

Synapse

Junction between neurons where impulses are transmitted chemically.

Presynaptic Membrane

Axon terminal membrane releasing neurotransmitters.

Postsynaptic Membrane

Membrane of the next cell bearing neurotransmitter receptors.

Synaptic Vesicle

Tiny sac in synaptic knob containing neurotransmitter molecules.

Neurotransmitter

Chemical messenger released at synapses to transmit impulses.

Excitatory Transmitter

Neurotransmitter that increases the likelihood a neuron will fire (e.g., acetylcholine).

Inhibitory Transmitter

Neurotransmitter that decreases the likelihood a neuron will fire (e.g., GABA).

Integration (Neural)

Summation of excitatory and inhibitory inputs determining neuron firing.

Ganglion

Collection of neuron cell bodies in the PNS.

Cranial Nerves

Twelve pairs of nerves serving head, neck, face; part of PNS.

Reflex Arc

Automatic pathway producing an involuntary response to a stimulus.

Receptor

Sense organ that generates a nerve impulse.

Effector

Muscle or gland that carries out a response.

Dorsal Root Ganglion

Cluster of sensory neuron cell bodies near the spinal cord.

Medulla Oblongata

Brainstem region controlling heart rate, breathing, and reflexes.

Thalamus

Central relay station for sensory impulses (except smell) to the cerebrum.

Cerebellum

Brain region coordinating balance, posture, and skeletal muscle movements.

Hypothalamus

Homeostasis center linking nervous and endocrine systems; controls pituitary.

Corpus Callosum

Thick band of fibers connecting the two cerebral hemispheres.

Cerebrum

Largest brain part responsible for intellect, memory, and sensation.

Cerebral Cortex

Outer gray matter layer of the cerebrum.

Frontal Lobe

Cerebral lobe for movement, problem-solving, higher intellect.

Parietal Lobe

Cerebral lobe processing touch, pain, speech understanding.

Temporal Lobe

Cerebral lobe for hearing, smell, memory of experiences.

Occipital Lobe

Cerebral lobe devoted to vision.

Insula

Fifth cerebral lobe involved in diverse poorly understood functions.

Extrapyramidal System

Descending white-matter tracts controlling body movement and posture.

Basal Nuclei

Deep brain masses involved in motor control; part of extrapyramidal system.

Limbic System

Brain network governing emotions, memory, and learning.

Short-Term Memory

Temporary storage of information requiring new synaptic activity.

Stimulant Drug

Substance that enhances excitatory transmission or blocks inhibition.

Depressant Drug

Substance that enhances inhibition or blocks excitatory transmission.

GABA (Gamma-aminobutyric acid)

Major inhibitory neurotransmitter in the CNS.

Acetylcholine (ACh)

Excitatory transmitter at neuromuscular junctions; parasympathetic mediator.

Dopamine

Neurotransmitter linked to reward, movement; deficient in Parkinson’s.

Norepinephrine (Noradrenalin)

Excitatory transmitter of the sympathetic nervous system.

Serotonin

Neurotransmitter influencing mood, sleep; low levels tied to depression.

Amphetamines

Stimulants that mimic noradrenalin and boost dopamine release.

Cocaine

Drug that blocks dopamine reabsorption, prolonging its effect.

THC (in Marijuana)

Psychoactive compound binding cannabinoid receptors causing relaxation.

Tranquilizers

Drugs that enhance GABA action; overdose can be fatal.

LSD

Hallucinogen affecting serotonin and dopamine pathways.

Nicotine

Stimulant that enhances acetylcholine activity.

Alcohol

Depressant that enhances GABA signaling.

Heroin

Narcotic that blocks pain signal transmission.

Parkinson’s Disease

Movement disorder caused by dopamine deficiency.

Alzheimer’s Disease

Progressive memory-loss disorder affecting the limbic system.

Huntington’s Chorea

Genetic disorder due to GABA malfunction causing progressive breakdown.

Epilepsy

Seizure disorder from miscommunication between RAS and cortex.

Cerebral Palsy

Motor disability from oxygen shortage to brain during birth.

Schizophrenia

Psychiatric disorder linked to excess dopamine causing hallucinations.

Depression

Mood disorder associated with low serotonin and/or norepinephrine.