AP Psychology Unit 1.3: The Neuron and Neural Firing

Vocabulary study guide flashcards covering neuron structure and function, neural firing process, communication disorders, neurotransmitters, hormones, and psychoactive drugs.

Neuron

The basic structural and functional unit of the nervous system; a specialized cell built to receive and transmit information.

Glial Cells

Support cells that nourish and insulate neurons (forming myelin), guide neural connections, and clean up waste in the nervous system.

Reflex Arc

A simple, automatic neural pathway — sensory neuron to interneuron to motor neuron — that produces a quick reflex without input from the brain.

Sensory Neurons

Neurons that carry incoming information from the body's sensory receptors toward the brain and spinal cord.

Motor Neurons

Neurons that carry outgoing commands from the brain and spinal cord to the body's muscles and glands.

Interneurons

Neurons located within the brain and spinal cord that connect sensory input to motor output and communicate internally.

Resting Potential

The stable, slightly negative electrical charge (about $-70\,\text{mV}$) of a neuron's interior when it is not firing.

Threshold

The level of stimulation that must be exceeded before a neuron will fire an action potential.

Depolarization

The shift in a neuron's charge from negative toward positive as positive ions rush in, part of the firing process.

All-or-Nothing Principle

A neuron's response rule: it either fires with full, uniform strength once threshold is reached, or it does not fire at all.

Refractory Period

A brief resting pause after a neuron fires, during which it cannot fire again as it resets for the next signal.

Reuptake

The process by which a sending neuron reabsorbs excess neurotransmitters from the synapse after a signal is sent.

Multiple Sclerosis

An autoimmune disease that damages the myelin sheath on axons, slowing or disrupting neural communication.

Myasthenia Gravis

A disorder in which the immune system attacks acetylcholine receptors, causing muscle weakness and fatigue.

Excitatory Neurotransmitter

A chemical messenger that increases the likelihood the receiving neuron will fire an action potential.

Inhibitory Neurotransmitter

A chemical messenger that decreases the likelihood the receiving neuron will fire an action potential.

Dopamine

Influences movement, learning, attention, and reward/motivation; oversupply is linked to schizophrenia, undersupply to Parkinson's disease.

Serotonin

Affects mood, hunger, sleep, and arousal; undersupply is linked to depression.

Norepinephrine

Affects alertness and arousal; undersupply can reduce alertness and depress mood.

Glutamate

A major excitatory neurotransmitter involved in memory; oversupply can overstimulate the brain and trigger migraines or seizures.

GABA (gamma-aminobutyric acid)

The brain's major inhibitory neurotransmitter; undersupply is linked to seizures, tremors, and insomnia.

Substance P

A neurotransmitter that plays a key role in transmitting and perceiving pain signals.

Endorphins

Neurotransmitters that influence the perception of pain and pleasure, often called the body's natural painkillers.

Acetylcholine

Enables muscle action, learning, and memory; undersupply is linked to Alzheimer's disease.

Hormones

Chemical messengers produced by the endocrine glands that travel through the bloodstream and affect other tissues.

Adrenaline

A hormone (also called epinephrine) that raises heart rate, blood pressure, and blood sugar to prepare the body for fight-or-flight.

Leptin

A hormone that signals the brain to reduce appetite, producing a feeling of fullness.

Ghrelin

A hormone that stimulates appetite, producing a feeling of hunger.

Melatonin

A hormone that helps regulate the sleep-wake cycle.

Oxytocin

A hormone associated with social bonding, trust, and feelings of love/attachment.

Agonist Drugs

Drugs that mimic a neurotransmitter's effects or increase its release/action at the synapse.

Antagonist Drugs

Drugs that block a neurotransmitter's effects or occupy its receptor site, preventing normal activity.

Tolerance

The diminishing effect of a drug with repeated use, so larger doses are needed to produce the same effect.

Stimulants

Drugs that excite neural activity and speed up body functions (e.g., caffeine, cocaine).

Caffeine

A mild stimulant that increases alertness by blocking receptors for adenosine, a chemical that promotes drowsiness.

Cocaine

A powerful, fast-acting stimulant that produces a euphoric rush by blocking the reuptake of dopamine.

Depressants

Drugs that slow neural activity and body functions (e.g., alcohol).

Alcohol

A depressant that slows neural processing, reduces inhibitions, and impairs judgment and memory.

Hallucinogens

Drugs that distort perception and evoke sensory images in the absence of sensory input (e.g., LSD).

Marijuana

A drug (from the cannabis plant) with mild hallucinogenic effects that can relax, produce mild euphoria, and impair memory.

Opioids

Opium and its derivatives that depress neural activity and relieve pain by mimicking the brain's own endorphins.

Heroin

A powerful, highly addictive opioid derived from morphine.

Addiction

A compulsive craving for and use of a substance (or behavior) despite known harmful consequences.

Withdrawal

The discomfort and distress that follow when use of an addictive drug is discontinued.