Unit One

Epigenetics

How environmental factors (like stress/diet) 'switch' genes on or off without changing DNA.

Neuroplasticity

The brain's ability to reorganize itself or build new pathways after damage.

Glial Cells

Cells that support, nourish, and protect neurons.

Reflex Arc

An automatic signal that goes to the spinal cord and back to the muscle before reaching the brain.

Central Nervous System (CNS)

The brain and spinal cord; the body's decision-maker.

Peripheral Nervous System (PNS)

The 'wires' connecting the CNS to the rest of the body.

Afferent (Sensory) Neurons

Neurons that carry incoming information from senses toward the brain.

Efferent (Motor) Neurons

Neurons that carry outgoing information exiting the brain to muscles.

Somatic Nervous System

The part of the PNS that controls voluntary skeletal muscles.

Autonomic Nervous System

The part of the PNS that controls involuntary functions (heart, glands).

Sympathetic Division

Arouses the body for 'Fight or Flight' (increases heart rate, dilates pupils).

Parasympathetic Division

Calms the body for 'Rest and Digest'.

Action Potential

A brief electrical charge that travels down an axon to send a message.

Dendrites

Branching extensions that receive messages from other cells.

Soma

The cell body; maintains the health of the neuron.

Axon

Long fiber that passes messages away from the cell body.

Myelin Sheath

Fatty tissue layer that insulates the axon and speeds up the signal.

Nodes of Ranvier

The gaps in the myelin sheath where the signal 'jumps'.

Synaptic Gap

The tiny fluid-filled space between neurons.

Depolarization

When positive ions rush into the neuron, making it fire.

Resting Potential

The state of a neuron when it is charged and ready but not yet firing.

Reuptake

When the sending neuron reabsorbs leftover neurotransmitters.

Agonists

Drugs that mimic or enhance a neurotransmitter.

Antagonists

Drugs that block or inhibit a neurotransmitter.

Acetylcholine (ACh)

Enables muscle action and memory; linked to Alzheimer's.

Dopamine

Reward, pleasure, and movement; linked to Schizophrenia (too much) and Parkinson’s (too little).

Serotonin

Affects mood, hunger, and sleep; linked to depression.

Endorphins

Natural painkillers released during exercise or pain.

GABA

Major inhibitory neurotransmitter; stops the brain from over-firing.

Glutamate

Major excitatory neurotransmitter; involved in memory.

Medulla

Controls heartbeat and breathing.

Pons

Coordinates movement and controls sleep/dreams.

Cerebellum

Coordinates balance and voluntary muscle movement.

Reticular Activating System (RAS)

Controls arousal and alertness.

Thalamus

The brain's sensory switchboard (all senses except smell).

Hypothalamus

Maintains homeostasis (hunger, thirst, body temp) and controls the pituitary.

Amygdala

Linked to emotion, specifically fear and aggression.

Hippocampus

Processes new memories for permanent storage.

Corpus Callosum

Nerve fibers connecting the two hemispheres.

Frontal Lobe

Planning, decision-making, and voluntary movement.

Parietal Lobe

Processes sensory input for touch and body position.

Temporal Lobe

Responsible for hearing and language.

Occipital Lobe

Responsible for visual processing.

Motor Cortex

Area at the rear of frontal lobe that controls voluntary movement.

Somatosensory Cortex

Area at the front of parietal lobe that processes touch.

Broca’s Area

Responsible for producing speech (Frontal Lobe).

Wernicke’s Area

Responsible for understanding speech (Temporal Lobe).

Split Brain

Condition where the corpus callosum is cut to stop seizures.

fMRI

Shows brain function by tracking blood flow.

EEG

Measures electrical activity (brain waves).

Beta Waves

Brain waves of an alert, waking state.

Alpha Waves

Brain waves of a relaxed, awake state.

Delta Waves

Large, slow brain waves of deep sleep (Stage 3).

REM Sleep

Paradoxical sleep where muscles are paralyzed but brain is active; dreaming occurs.

REM Rebound

Tendency for REM to increase after sleep deprivation.

Activation-Synthesis

Theory that dreams are the brain's attempt to make sense of random neural static.

Consolidation Theory

Sleep helps transfer info into long-term memory.

Sensory Transduction

Converting physical energy (light/sound) into neural impulses.

Absolute Threshold

Minimum stimulus needed to detect it 50% of the time.

Just-noticeable Difference (JND)

Minimum difference between two stimuli to detect change.

Weber’s Law

Two stimuli must differ by a constant percentage to be perceived as different.

Sensory Adaptation

Diminished sensitivity to a constant stimulus (e.g., a smell goes away).

Retina

Light-sensitive inner surface of the eye.

Rods

Detect black, white, and gray; used for night vision.

Cones

Detect fine detail and color; used in daylight.

Fovea

Central point in the retina where cones cluster; sharpest vision.

Trichromatic Theory

The retina has three color receptors (Red, Green, Blue).

Opponent-Process Theory

Color is processed in opposing pairs (Red-Green, Blue-Yellow); explains afterimages.

Place Theory

We hear pitch based on where the cochlea is stimulated.

Frequency Theory

We hear pitch based on the rate of neural impulses.

Sensorineural Deafness

Hearing loss from damage to the cochlea or auditory nerve.

Conduction Deafness

Hearing loss from damage to the ear's mechanical system.

Gate Control Theory

The spinal cord blocks or allows pain signals to reach the brain.

Vestibular Sense

Monitors body position and balance (controlled by inner ear).

Kinesthesis

Sensing the position and movement of individual body parts.