AP Psychology – Unit 3: Biological Bases of Behavior

Neuron

a nerve cell that sends messages in the body Example: helping you move your hand when it touches something hot

Dendrite

branches of a neuron that receive messages Example: dendrites pick up signals from other neurons

Axon

the long part of a neuron that sends messages Example: the axon carries the message to the next neuron

Myelin Sheath

a fatty layer around the axon that speeds up messages Example: insulation around a wire helping signals move fast

Action Potential

a brief electrical charge that travels down the axon Example: the signal your brain sends to move your arm

Threshold

the level of stimulation needed to trigger an action potential Example: turning on a light switch only after pushing hard enough

Synapse

the tiny gap between neurons where messages pass Example: a bridge where neurotransmitters travel

Neurotransmitters

chemicals that carry messages across the synapse Example: dopamine helps with movement and pleasure

Reuptake

when extra neurotransmitters are taken back by the neuron Example: recycling unused chemicals

Endorphins

natural painkillers in the brain Example: released during exercise to reduce pain

Nervous System

the body’s speedy communication network of neurons Example: helps you feel and react quickly

Central Nervous System (CNS)

the brain and spinal cord Example: the command center of the body

Peripheral Nervous System (PNS)

all the nerves outside the brain and spinal cord Example: messengers connecting body to brain

Nerves

bundles of axons that carry messages Example: spinal nerves control movements like walking

Sensory Neurons

carry info from body to brain Example: tell your brain when you touch something hot

Motor Neurons

carry info from brain to muscles Example: move your hand away from a flame

Interneurons

neurons in the brain and spinal cord that process info Example: connect sensory and motor neurons

Somatic Nervous System

controls voluntary movements Example: moving your arms and legs

Autonomic Nervous System

controls automatic body functions Example: breathing and heartbeat

Sympathetic Nervous System

prepares the body for stress ("fight or flight") Example: your heart races when you're scared

Parasympathetic Nervous System

calms the body after stress ("rest and digest") Example: your heartbeat slows after danger passes

Reflex

A quick, automatic response to a stimulus.
Example: Pulling your hand away from a hot stove.

Endocrine System

a system of glands that release hormones Example: the thyroid gland controls metabolism

Hormones

chemical messengers made by glands Example: adrenaline gives you energy in danger

Adrenal Glands

release hormones during stress Example: pump adrenaline when you're nervous

Pituitary Gland

the “master gland” that controls other glands Example: helps with growth and puberty

Lesion

tissue destruction in the brain Example: a brain lesion may cause loss of speech

EEG (Electroencephalogram)

records brain waves with electrodes Example: used to study sleep or seizures

CT (Computed Tomography) Scan

X-ray images of the brain Example: shows brain structure after injury

PET (Positron Emission Tomography) Scan

shows brain activity using radioactive glucose Example: shows which brain part is active while reading

MRI (Magnetic Resonance Imaging)

uses magnets to show brain structure Example: helps find brain damage

fMRI (Functional MRI)

shows both structure and activity of the brain Example: shows what part lights up during a task

Brainstem

the oldest part of the brain that controls basic life functions Example: controls heartbeat and breathing

Medulla

controls heartbeat and breathing Example: the part that keeps you alive

Pons

helps with movement and sleep Example: controls dreams and facial expressions

Thalamus

the brain's relay station for sensory info Example: sends sight and sound to the right brain parts

Reticular Formation

controls alertness and arousal Example: helps you stay awake in class

Cerebellum

controls balance and coordination Example: helps you ride a bike

Limbic System

a group of brain parts involved in emotions and memory Example: helps you feel fear or remember your birthday

Amygdala

linked to emotion

Hypothalamus

controls hunger

Hippocampus

helps with forming new memories Example: damaged in Alzheimer’s disease

Cerebral Cortex

the outer layer of the brain that controls thinking and sensing Example: helps you read

Frontal Lobes

control thinking

Parietal Lobes

process touch and body position Example: help you feel someone tap your shoulder

Occipital Lobes

process visual info Example: help you recognize objects

Temporal Lobes

process hearing and language Example: help you understand words

Motor Cortex

controls voluntary movements Example: sends signals to move your legs

Somatosensory Cortex

processes touch and body movement sensations Example: helps you feel pressure or warmth

Association Areas

involved in higher mental functions like learning and memory Example: connect new info to what you know

Plasticity

the brain's ability to change and adapt Example: a blind person’s brain uses touch to read Braille

Neurogenesis

the formation of new neurons Example: learning helps grow brain cells

Corpus Callosum

connects the two brain hemispheres Example: lets the left and right sides share info

Split Brain

when the corpus callosum is cut

Consciousness

your awareness of yourself and surroundings Example: being awake and alert

Cognitive Neuroscience

study of how brain activity is linked to thinking and behavior Example: watching brain activity during a decision

Dual Processing

the brain works on conscious and unconscious tracks Example: driving while daydreaming

Behavior Genetics

study of how genes and environment affect behavior Example: studying twins to see what’s inherited

Environment

every influence around you Example: your home

Chromosomes

structures that hold your DNA Example: humans have 46 chromosomes

DNA

the material that carries genetic info Example: determines your eye color

Genes

pieces of DNA that determine traits Example: influence how tall you are

Genome

all of your genetic material Example: the instructions to build you

Identical Twins

twins from the same egg and genetically identical Example: share 100% of genes

Fraternal Twins

twins from two eggs Example: like siblings sharing 50% of genes

Heritability

how much of a trait is due to genes Example: height is about 80% heritable

Interaction

how genes and environment work together Example: having talent but needing lessons to grow it

Epigenetics

study of how environment can turn genes on or off Example: stress can change how genes act

Natural Selection

traits that help survival are passed on Example: giraffes with long necks survive better

Mutation

a change in a gene Example: may cause disease or new traits