1.3

Neuron

A cell that sends messages in the brain and body.
Example: Neurons help you move your hand when you touch something hot.

Glial Cells

Support cells that protect and nourish neurons.

But they also send and recieive chemical signals to and from each other and to and from neurons
Example: They are like the “helpers” that keep neurons healthy.

Reflex Arc

The pathway that controls a quick, automatic response to danger.
Example: You pull your hand away from a hot stove without thinking.

Sensory Neurons

Carry information from the body to the brain.
Example: They tell your brain when you feel pain or heat.

Motor Neurons

Send messages from the brain to the muscles.
Example: They tell your muscles to move when you walk or run.

Interneurons

Connect sensory and motor neurons, processing information in the brain.
Example: They help you decide how to react to something you see.

All-or-Nothing Principle = NT

A neuron either fully fires or doesn’t fire at all.
Example: Like flipping a switch—there’s no "half-firing."

Depolarization = NT

When a neuron gets ready to fire by changing its electrical charge.
Example: It’s like charging up a battery before using it.

Refractory Period = NT

A short time when a neuron can't fire again after firing once.
Example: Like reloading after a shot is fired.

Action Potential = NT

The electrical signal that travels down a neuron when it fires.
Example: It’s like sending a message through a wire.

Resting Potential = NT

The state of a neuron when it’s not firing, but ready to fire.
Example: The neuron is like a loaded gun, waiting for a trigger.

Reuptake = NT

When neurotransmitters are taken back into the neuron after they’ve been used.
Example: It’s like recycling chemicals in the brain.

- Imagine neurotransmitters are like mail being sent from one neuron to another.
- Once the message is delivered, any extra mail is "picked up" and returned to the sender (the first neuron) for reuse.

Threshold (Firing Threshold) = NT

Level of electrical charge a neuron must reach before it triggers an action potential.

Multiple Sclerosis

A disease that damages the protective covering of neurons.

Example: It makes it hard to control muscles and movement

Myasthenia Gravis

A condition that weakens the muscles by blocking signals from nerves.

Example: People with this disease may have trouble lifting things or speaking clearly.

Excitatory Neurotransmitter

Makes a neuron more likely to fire.

Example: Like hitting the gas pedal in a car.

Inhibitory Neurotransmitter

Makes a neuron less likely to fire.
Example: Like pressing the brakes in a car.

Hormones

Chemical messengers that travel through the blood and affect the body.
Example: Hormones control growth, mood, and energy.

Dopamine = ENT & INT

A neurotransmitter that affects pleasure and reward (both excitatory and inhibitory).

Example: Dopamine is released when you eat something you love.

Serotonin = INT

An inhibitory neurotransmitter that affects mood and happiness.
Example: Low serotonin levels can make people feel sad or depressed.

Endorphins = I

Natural painkillers produced by the brain, reduce the feeling of sadness
Example: You feel endorphins after exercising, which makes you feel good.

Substance P

A neurotransmitter that sends pain messages.
Example: When you touch something hot, substance P makes you feel pain.

Acetylcholine = ACh + ENT

An excitatory neurotransmitter that helps with muscle movement and memory.
Example: Acetylcholine helps your muscles move when you lift something.

GABA = I

An inhibitory neurotransmitter that calms the brain.
Example: GABA helps you relax and fall asleep.

Glutamate = E

An excitatory neurotransmitter involved in learning and memory.
Example: Glutamate helps your brain store new information.

Norepinephrine = I

An inhibitory neurotransmitter that helps control stress and attention.
Example: Norepinephrine helps you stay focused in a stressful situation.

Melatonin = H

A hormone that controls sleep cycles.
Example: Melatonin helps you fall asleep at night.

Oxytocin = H

A hormone that promotes bonding and trust.
Example: Oxytocin is released when you hug someone you care about.

Adrenaline = H

A hormone that increases energy and alertness in stressful situations.
Example: Adrenaline kicks in when you’re scared or excited.

Leptin = H

A hormone that tells you when you’re full and to stop eating.
Example: Leptin helps control appetite and prevent overeating.

Ghrelin = H

A hormone that makes you feel hungry.
Example: Ghrelin levels rise before meals, making you want to eat.

Psychoactive Drugs

Drugs that affect the brain and change mood or behavior.
Example: Alcohol and caffeine are psychoactive drugs.

Agonist Drugs

Drugs that boost the effect of neurotransmitters.
Example:
Morphine – Mimics endorphins, which are natural painkillers in the body, reducing pain.

Nicotine – Mimics acetylcholine, stimulating pleasure and reward pathways.

Antagonist Drugs

Drugs that block neurotransmitters.
Example: Some drugs block dopamine to help treat schizophrenia.

Cocaine

A stimulant drug that increases dopamine levels, creating feelings of euphoria.
Example: Cocaine can cause extreme highs and dangerous health effects.

Stimulants

Drugs that speed up brain activity.
Example: Caffeine and nicotine are common stimulants.

Caffeine

A stimulant found in coffee and tea that boosts energy and alertness.
Example: Drinking coffee makes you feel more awake because of caffeine.

Hallucinogens

Drugs that cause people to see or hear things that aren’t real.
Example: LSD is a hallucinogen that can make people hallucinate.

Depressants

Drugs that slow down brain activity.
Example: Alcohol is a depressant that can make you feel relaxed but slow your reactions

Alcohol

A depressant drug that reduces brain activity and coordination.
Example: Drinking alcohol can make you feel calm but also slow your reflexes.

Heroin

An opioid drug that relieves pain but is highly addictive.
Example: Heroin can cause a short-term high but has dangerous long-term effects.

Marijuana

A drug that can act as a depressant, stimulant, or hallucinogen.
Example: Marijuana can relax you but may also cause hallucinations in high doses.

Opioids

Pain-relieving drugs that are highly addictive.
Example: Prescription opioids like morphine are used to relieve pain but can lead to addiction.

Tolerance

Needing more of a drug to get the same effect.
Example: Over time, you might need more caffeine to feel energized.

Addiction

Being unable to stop using a drug, even when it causes harm.
Example: Addiction makes a person keep using drugs even if it hurts their health.

Withdrawal

Unpleasant symptoms when stopping drug use.
Example: A person might feel shaky and anxious when they stop using alcohol.

Dependence

Needing a drug to feel normal.
Example: Someone with drug dependence feels sick if they don’t take the drug.