AP Psychology Unit 1.3 Vocab

Action potential

A brief electrical charge that travels down the axon of a neuron, triggering the release of neurotransmitters.

All-or-nothing principle

Once a neuron fires, it fires completely; the strength of the action potential does not vary.

Axon

The long fiber of a neuron that carries impulses away from the cell body to other neurons or muscles.

Cell body (soma)

The main part of a neuron that contains the nucleus and keeps the cell alive.

Dendrites

Branch-like extensions that receive signals from other neurons.

Depolarization

When positive ions enter the neuron, making it more likely to fire an action potential.

Glial cells

Support cells that nourish, protect, and help maintain neurons.

Interneurons

Neurons in the brain and spinal cord that process information between sensory and motor neurons.

Motor neurons (efferent neurons)

Carry information from the brain and spinal cord to muscles and glands.

Multiple sclerosis (MS)

A disease where the immune system attacks the myelin sheath, slowing or blocking neural transmission.

Myasthenia gravis

A disorder causing weakness in muscles due to problems with acetylcholine receptors.

Myelin sheath

Fatty tissue that covers axons, speeding up neural impulses.

Neural transmission

The process by which neurons send messages through electrical impulses and chemical neurotransmitters.

Neuron

A nerve cell that transmits information throughout the nervous system.

Reflex

An automatic, involuntary response to a stimulus.

Reflex arc

The pathway of a reflex, involving sensory input, interneurons, and motor output.

Refractory period

A brief time after an action potential when a neuron cannot fire again.

Resting potential

The state of a neuron when it’s not firing; inside of the cell is negatively charged relative to the outside.

Reuptake

The process of neurotransmitters being reabsorbed by the sending neuron.

Reuptake inhibitors

Drugs that block reuptake, increasing the amount of neurotransmitter available in the synapse.

Sensory neurons (afferent neurons)

Carry information from sensory receptors to the brain and spinal cord.

Synapse

The gap between neurons where neurotransmitters are released.

Threshold

The level of stimulation needed to trigger a neural impulse.

Acetylcholine (ACh)

Enables muscle movement, learning, and memory; linked to Alzheimer’s disease when lacking.

Adrenaline/Epinephrine

Hormone and neurotransmitter involved in the fight-or-flight response.

Dopamine

Influences movement, learning, attention, and emotion; linked to schizophrenia when excessive and Parkinson's disease when deficient.

Endocrine system

The body’s system of glands that secrete hormones into the bloodstream.

Endorphins

Natural painkillers that produce euphoria and reduce pain.

GABA (gamma-aminobutyric acid)

The main inhibitory neurotransmitter; low levels are linked to anxiety and seizures.

Ghrelin

Hormone that increases hunger.

Glutamate

The main excitatory neurotransmitter; plays a role in memory but can lead to migraines or seizures in excess.

Leptin

Hormone that reduces hunger and helps regulate body weight.

Melatonin

Hormone that regulates sleep-wake cycles, produced by the pineal gland.

Norepinephrine

Helps control alertness and arousal; undersupply can lead to mood depression.

Neurotransmitter

Chemical messenger that transmits signals across the synapse.

Oxytocin

Hormone linked to bonding, trust, and social behavior.

Serotonin

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

Substance P

Neurotransmitter involved in transmitting pain signals.

Addiction

Compulsive drug use despite harmful consequences, caused by changes in brain reward pathways.

Agonists

Drugs that mimic or enhance the effects of neurotransmitters.

Alcohol

Depressant that slows neural activity and impairs judgment, memory, and motor skills.

Antagonists

Drugs that block or inhibit neurotransmitter action.

Caffeine

Stimulant that increases alertness by blocking adenosine receptors.

Cocaine

Powerful stimulant that increases dopamine levels, causing euphoria followed by a crash.

Depressants

Drugs that slow down the central nervous system (e.g., alcohol, barbiturates).

Hallucinogens

Drugs that distort perceptions and evoke sensory images (e.g., LSD, psilocybin).

Heroin

An opioid that produces euphoria and pain relief but is highly addictive.

Marijuana

A mild hallucinogen that relaxes, distorts time, and can impair memory.

Opioids

Drugs that relieve pain and produce pleasure by mimicking endorphins (e.g., morphine, heroin).

Psychoactive drugs

Chemical substances that alter perception, mood, and consciousness.

Stimulants

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

Tolerance

Reduced responsiveness to a drug, requiring more for the same effect.

Withdrawal

Physical and psychological symptoms that occur when drug use stops.

Hormones

Chemical messengers released by endocrine glands that travel through the bloodstream to target organs.