The Brain

Cell body

soma, serves as the cell's life support system.

Dendrites

Structures that receive messages from other neurons.

Axon

The part of a neuron that passes messages through the cell body.

Neural impulse

The action potential; an electrical signal that travels down the axon.

Myelin sheath

A protective layer that covers the axon and speeds up the neural impulse.

Terminal axon branch

The part of the neuron that forms junctions with other neurons.

Glial cells

Supportive cells in the nervous system; there are about 10 glial cells for every neuron.

Synaptic gap

The space between neurons where neurotransmitters pass.

Reuptake

The process of collecting excess neurotransmitters from the synaptic gap.

Resting potential

The state of a neuron when ions are at opposite ends of the axon, making it polarized.

Action potential

Triggered when the threshold is met and ions become depolarized, causing the neuron to activate.

Threshold

The minimum amount of neurotransmitters that results in an effect; beyond this point, additional neurotransmitters don't influence the outcome.

All-or-nothing

The principle that once the threshold is met, the neuron will either fire or not fire.

Refractory period

The time during which ions are polarized again, resetting the resting potential.

ACH (acetylcholine)

A neurotransmitter that controls muscle action, learning, and memory; too much can cause seizures and too little can lead to Alzheimer's.

Dopamine

A neurotransmitter that controls attention and emotion; too much can lead to schizophrenia and too little to Parkinson's or ADHD.

Serotonin

A neurotransmitter that affects mood and induces a calming/happy feeling; too little can lead to clinical depression.

Norepinephrine

A neurotransmitter that controls alertness; too little can cause depression.

GABA

The main inhibitory neurotransmitter; too little can lead to seizures and too much causes insomnia and anxiety.

Glutamate

The main excitatory neurotransmitter; controls memory; too much can cause overstimulation and headaches.

Endorphins

Naturally occurring opiates released in response to pain; too much synthetic opioid use can decrease endorphin production.

Agonist

A substance that mimics neurotransmitters and activates receptors.

Antagonist

A substance that blocks neurotransmitters from binding to receptors.

Phrenology

The study of skull shape to determine personality traits.

Gall

The father of phrenology, who was known for his celebrity status.

Phineas Gage

A man whose brain injury helped to establish that the frontal lobe controls personality.

MRI

A medical imaging technique that creates detailed images of the body's structures without using radiation.

fMRI

An imaging technique used to measure and map brain activity by detecting changes associated with blood flow.

CAT scan

An imaging technique that uses x-rays to create detailed images of the inside of the body.

PET scan

A scan that detects metabolic activity by tracking where calories are used in the brain.

EEG scan

A method to examine brain waves during different consciousness levels; can also identify sensory processing in infants.

MEG scan

An imaging technique used to detect magnetic fields produced by neural activity.

Medulla

The part of the brain that controls heartbeat and breathing.

Oblongata

The area connecting the brainstem with the spinal cord.

Reticular Formation

A part of the brainstem that regulates arousal; crucial for consciousness.

Basal Ganglia

A group of nuclei in the brain responsible for controlling movements and behaviors.

Pons

A structure that helps with sleeping and dreaming by connecting the brainstem with the cerebellum.

Cerebellum

The part of the brain that controls coordination and balance.

Thalamus

The brain's sensory switchboard, directing sensory data to appropriate processing areas.

Hippocampus

The brain structure responsible for processing new memories.

Amygdala

The region of the brain that controls basic emotions like fear and aggression.

Hypothalamus

A critical region that regulates hunger, thirst, body temperature, and connects to the pituitary gland.

Cerebral cortex

The outer layer of the brain covering the cerebrum.

Frontal Lobe

The brain's region responsible for personality, reasoning, and morality.

Parietal Lobe

The brain area associated with sensory perception.

Occipital Lobe

The region of the brain that processes visual information.

Temporal Lobe

The part of the brain associated with hearing and language processing.

Afferent neurons

Also known as sensory neurons, they carry signals to the central nervous system.

Efferent neurons

Also known as motor neurons, they transmit commands from the central nervous system to muscles.

Sensory neurons

Neurons that detect sensory information and send it to the spinal cord.

Interneurons

Neurons that connect sensory neurons with motor neurons.

Motor neurons

Neurons that control movement by sending signals from the spinal cord to muscles.

Corpus callosum

The structure connecting the two brain hemispheres, which may be severed in some epilepsy treatments.

Association areas

Brain regions that are not cortexes; the presence of more of these is linked to higher intelligence.

Pituitary gland

A gland in the brain regulated by the hypothalamus that controls other glands and growth.

Pineal gland

The gland responsible for producing melatonin.

Thyroid gland

A gland that regulates metabolism and can affect mental capabilities.

Adrenal glands

Glands that release adrenaline and cortisol; involved in stress and the fight-or-flight response.

Pancreas

An organ that regulates insulin and blood sugar, associated with diabetes.

Ovaries/Testes

Gonads that produce sex hormones, estrogen in ovaries and testosterone in testes.

Broca's area

The region in the left frontal lobe responsible for speech production.

Wernicke's area

The area in the left temporal lobe responsible for language comprehension.