1.3 B/C

Action potential

A brief electrical charge that travels down a neuron's axon when it fires.

All or nothing principle

The concept that a neuron either fires completely or does not fire at all; there are no partial action potentials.

Depolarization

The process where a neuron's internal charge becomes less negative as positive ions rush inside.

Reuptake

The process where a sending neuron reabsorbs excess neurotransmitter molecules from the synapse.

Multiple Sclerosis

A disease where the immune system attacks the myelin sheath of neurons, slowing communication.

Neurotransmitters

Chemical messengers released from neurons that cross synapses to carry signals.

Excitatory neurotransmitters

Chemical messengers that make a receiving neuron more likely to generate an electrical signal and fire.

Dopamine

A neurotransmitter involved in movement, attention, learning, and the brain's reward system.

Norepinephrine

A neurotransmitter involved in alertness, arousal, mood, and the body's stress response.

GABA

The brain's main inhibitory neurotransmitter, reducing neural activity and linked to relaxation.

Substance P

A neurotransmitter involved in the transmission of pain signals to the brain.

Hormones

Chemical messengers released by endocrine glands directly into the bloodstream to influence bodily functions.

Leptin

A hormone released by fat cells that signals the brain to reduce appetite and regulate energy.

Melatonin

A hormone produced by the pineal gland that regulates sleep-wake cycles.

Refractory Period

A brief time after a neuron fires during which it cannot fire again until it resets.

Resting potential

The electrical charge of a neuron when it is not firing, with the inside negatively charged.

Threshold

The minimum stimulation needed to detect a stimulus or trigger a neural impulse.

Myasthenia Gravis

A chronic autoimmune disorder impairing communication between nerves and muscles.

Inhibitory Neurotransmitters

Chemicals that decrease the likelihood a neuron will fire an action potential.

Serotonin

A neurotransmitter that regulates mood, hunger, sleep, and arousal.

Glutamate

The brain's primary excitatory neurotransmitter, important for learning and memory.

Endorphins

Natural neurotransmitters that act like painkillers and produce feelings of pleasure.

Acetylcholine

A neurotransmitter linked to learning, memory, and muscle movement.

Endocrine System

A network of glands that produce and release hormones directly into the bloodstream.

Adrenaline

A hormone and neurotransmitter released in response to stress, increasing heart rate and energy.

Ghrelin

A hormone released by the stomach that stimulates hunger and increases appetite.

Oxytocin

A hormone involved in social bonding, trust, and emotional attachment.

Psychoactive Drugs

Substances that alter perception, mood, consciousness, or behavior by affecting neurotransmitters.

Substance Abuse Disorder

Continued substance craving and use despite significant life disruption or physical risk.

Antagonist

Drugs or chemicals that block or inhibit the action of a neurotransmitter.

Stimulants

Drugs that increase neural activity and arousal (e.g., caffeine, nicotine, cocaine).

Caffeine

A psychoactive stimulant drug that excites neural activity by blocking adenosine receptors.

Cocaine

A powerful, addictive stimulant psychoactive drug derived from the coca plant.

Methamphetamines

A powerfully addictive stimulant drug that speeds up CNS activity and triggers rapid dopamine release.

Ecstasy

A synthetic stimulant and mild hallucinogen that produces euphoria and social intimacy.

Opioids

Psychoactive depressant drugs that reduce neural activity, relieve pain, and produce euphoria.

Heroin

A psychoactive drug that depresses CNS activity, relieves pain, and acts as an endorphin agonist.

Addiction

Compulsive drug craving and use, continuing despite adverse consequences.

Agonist

Drugs or chemicals that mimic or increase the action of a neurotransmitter.

Reuptake Inhibitor

A substance that interferes with the reabsorption of neurotransmitters by presynaptic neurons.

Depressants

Psychoactive drugs that slow down neural activity and body functions.

Barbiturates

Drugs that reduce anxiety and induce sleep by depressing central nervous system activity.

Alcohol

A psychoactive drug that slows down the central nervous system and reduces judgment.

Hallucinogens

Psychoactive drugs that distort perceptions and evoke sensory images without actual stimuli.

Near-death experience

An altered state of consciousness reported by a person after a close brush with death.

Marijuana

A mild hallucinogen that distorts perceptions and triggers a variety of effects.

LSD

A powerful hallucinogenic drug that distorts perceptions and evokes sensory images.

Tolerance

The brain's reduced response to a drug after repeated use, leading to larger required doses.