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.

Neurotransmitters & Hormones

NTMs, Hormones – Chemical messengers; neurotransmitters act in the nervous system, while hormones act in the bloodstream.
Acetylcholine (ACh) – Enables muscle movement, learning, and memory. Lack of ACh is linked to Alzheimer’s disease.
Adrenaline/Epinephrine – Hormone and neurotransmitter involved in the fight-or-flight response.
Dopamine – Influences movement, learning, attention, and emotion; too much is linked to schizophrenia, too little to Parkinson’s disease.
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 linked to anxiety and seizures.
Ghrelin – Hormone that increases hunger.
Glutamate – The main excitatory neurotransmitter; involved in memory, but too much can cause migraines or seizures.
Hormones – Chemical messengers released by endocrine glands that travel through the bloodstream to target organs.
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 depress mood.
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.

Drugs & Effects

Drugs – Substances that alter perception, mood, or behavior by affecting neurotransmission.
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.