AP Psych Vocab #4 | Unit 1

Neuron

a nerve cell; the basic building block of the nervous system

Cell Body

the part of a neuron that contains the nucleus; the cell’s life-support center

dendrites

a neuron’s often bushy, branching extensions that receive and integrate messages, conducting impulses toward the cell body.

axon

the segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands

myelin sheath

a fatty tissue layer segmentally encasing the axons of some neurons; it enables vastly greater transmission speed as neural impulses hop from one node to the next.

glial cells (glia)

cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory

action potential

a neural impulse; a brief electrical charge that travels down an axon

threshold

the level of stimulation required to trigger a neural impulse

refractory period

in neural processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state

all-or-none response

a neuron’s reaction of either firing (with a full-length strength response) or not firing.

synapse

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. the tiny gap at this junction is called the synaptic gap or synaptic cleft.

neurotransmitters

chemical messengers that cross the synaptic gap between neurons. when released by the sending neuron, they travel across the synapse and bind receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

reuptake

a neurotransmitter’s reabsorption by the sending neuron

endorphins

natural, opioid-like neurotransmitters linked to pain control and to pleasure; “morphine within”

agonist

a molecule that increases a neurotransmitter’s action

antagonist

a molecule that inhibits or blocks a neurotransmitter’s action

endocrine system

the body’s “slow” chemical communication system; a set of glands and fat tissue that secrete hormones into the bloodstream

hormones

chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues.

psychoactive drug

a chemical substance that alters the brain, causing changes in perceptions and moods

substance use disorder

a disorder characterized by continued substance use despite resulting life disruption

depressants

drugs that reduce neural activity and slow body functions

tolerance

the diminishing effect with regular use of the same dose of a drug, requiring the user to take larger and larger doses before experiencing the drug’s effect

addiction

an everyday term for compulsive substance use (and sometimes for dysfunctional behavior patterns, such as out-of-control gambling) that continue despite harmful consequences

withdrawal

the discomfort and distress that follow discontinuing an addictive drug or behavior.

barbiturates

drugs that depress central nervous system activity, reducing anxiety but impairing memory and judgement

opioids

opium and its derivatives; they depress neural activity, temporarily lessening pain and anxiety

stimulants

drugs that excite neural activity and speed up body functions

hallucinogens

psychedelic (“mind manifesting”) drugs that distort perceptions and evoke sensory images in the absence of sensory input

near-death experience

an altered state of consciousness reported after a close brush with death (such as a cardiac arrest); often similar to drug-induced hallucinations

Acetylcholine (ACh)

Muscle movement, learning, memory, and attention.

Dopamine

Movement, reward, motivation, attention, and learning.

Serotonin

Regulates mood, sleep, appetite, and arousal

GABA

Main inhibitory neurotransmitter; slows and calms neural activity.

Glutamate

Main excitatory neurotransmitter; increases neural activity and helps with learning and memory.

Substance P

Transmits pain signals from the body to the brain.

Agonist (function)

Increases or mimics a neurotransmitter's effects

Norepinephrine

Alertness, arousal, attention, and the stress response.