brain

Autonomic nervous system

Controls involuntary bodily functions (e.g., heart rate, digestion).

Central Nervous System

The brain and spinal cord.

Parasympathetic nervous system

The 'rest and digest' system; calms the body.

Somatic nervous system

Controls voluntary muscle movements.

Sympathetic nervous system

The 'fight or flight' system; arouses the body.

Limbic system

Associated with emotions and drives; Includes the amygdala, hippocampus, and hypothalamus.

Cerebral Cortex

The outer layer of the brain responsible for higher-level processing.

Corpus callosum

The bundle of nerve fibers connecting the two cerebral hemispheres.

Action potential

A brief electrical charge that travels down an axon.

All-or-nothing principle

A neuron either fires completely or not at all.

Depolarization

The process during the action potential when sodium rushes into the cell causing the interior to become more positive.

Glial cells

Support, nourish, and protect neurons.

Interneurons

Neurons within the brain and spinal cord that communicate internally.

Reuptake

The reabsorption of neurotransmitters by the sending neuron.

Reuptake inhibitor

A substance that interferes with reuptake, increasing neurotransmitter levels in the synapse.

Refractory period

A brief resting pause after a neuron has fired.

Resting potential

The positive-outside/negative-inside state of a resting axon.

Threshold

The level of stimulation required to trigger a neural impulse.

Acetylcholine

Enables muscle action, learning, and memory.

Dopamine

Influences movement, learning, attention, and emotion.

Endorphins

Natural, opiate-like neurotransmitters linked to pain control and pleasure.

GABA (Inhibitory)

A major inhibitory neurotransmitter.

Glutamate (Excitatory)

A major excitatory neurotransmitter; involved in memory.

Norepinephrine

Helps control alertness and arousal.

Serotonin

Affects mood, hunger, sleep, and arousal.

Substance P

Involved in the transmission of pain messages to the brain.

Agonist

A molecule that increases a neurotransmitter's action.

Antagonist

A molecule that inhibits or blocks a neurotransmitter's action.

Adrenaline

Secreted by adrenal glands in response to stress; increases heart rate.

Ghrelin

Hormone secreted by empty stomach; sends 'I'm hungry' signals to the brain.

Leptin

Protein hormone secreted by fat cells; causes brain to increase metabolism and decrease hunger.

Melatonin

Hormone that helps regulate sleep-wake cycles.

Oxytocin

Linked to social bonding, trust, and sexual reproduction.

Amygdala

Two lima-bean-sized neural clusters linked to emotion (fear and aggression).

Brainstem

The oldest part and central core of the brain; responsible for automatic survival functions.

Cerebellum

The 'little brain'; processes sensory input, coordinates movement output and balance, and enables implicit memory.

Frontal lobe

Involved in speaking, muscle movements, and making plans/judgments.

Hippocampus

Processes explicit memories for storage.

Hypothalamus

Directs maintenance activities (eating, drinking, body temperature) and governs the endocrine system via the pituitary gland.

Medulla

The base of the brainstem; controls heartbeat and breathing.

Motor cortex

An area at the rear of the frontal lobes that controls voluntary movements.

Occipital lobe

Includes areas that receive information from the visual fields.

Parietal lobe

Receives sensory input for touch and body position.

Pituitary gland

The endocrine system's 'master gland'; regulates growth and controls other endocrine glands.

Prefrontal cortex

Part of the frontal lobe responsible for thinking, planning, and language.

Reticular formation

A nerve network in the brainstem that plays an important role in controlling arousal.

Somatosensory cortex

Area at the front of the parietal lobes that registers and processes body touch and movement sensations.

Temporal lobe

Includes the auditory areas, each receiving information primarily from the opposite ear.

Aphasia

Impairment of language, usually caused by left hemisphere damage.

Broca’s Area

Controls language expression; an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech.

Wernicke’s Area

Controls language reception; a brain area involved in language comprehension and expression; usually in the left temporal lobe.

Contralateral hemispheric organization

The principle that the left hemisphere controls the right side of the body and vice versa.

Split brain research

Study of patients with severed corpus callosa; reveals hemisphere specialization.

Plasticity

The brain's ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.

EEG

An amplified recording of the waves of electrical activity sweeping across the brain's surface.

fMRI

A technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans.

Lesioning

Tissue destruction; a naturally or experimentally caused destruction of brain tissue.

Multiple sclerosis

A disease in which the immune system eats away at the protective covering (myelin) of nerves.

Myasthenia gravis

A weakness and rapid fatigue of muscles under voluntary control.

Reflex arc

A relatively direct connection between a sensory neuron and a motor neuron that allows an extremely rapid response to a stimulus.