AP Psyc

Nature

The influence of genetic inheritance on behavior.

• Example: A child shows high musical ability at a young age, which may be due to inherited traits from musically talented parents.

Nurture

The influence of environmental factors and experiences on behavior.

• Example: A child becomes fluent in a second language because they grew up in a bilingual household.

Heredity

The passing of traits from parents to offspring through genes.

• Example: A person inherits brown eyes and curly hair from their parents.

Epigenetics

The study of how the environment can influence gene expression without altering the DNA sequence.

• Example: A person who experiences extreme stress may activate certain genes related to anxiety disorders.

Brain Plasticity

The brain’s ability to change and adapt as a result of experience.

• Example: After a stroke, a person relearns how to speak through therapy, using different parts of the brain.

Natural Selection

The evolutionary process where traits that improve survival and reproduction are passed on.

• Example: People with a better sense of smell in ancient times may have survived better, passing that trait on.

Evolutionary Perspective

A psychological approach that explains behavior through the lens of adaptation and survival.

• Example: Humans may have evolved a fear of snakes because avoiding them increased survival chances.

Eugenics

A discredited movement aimed at improving the genetic quality of the human population by selective breeding.

• Example: In the early 20th century, some governments sterilized individuals deemed “unfit” to reproduce.

Twin Studies

Research that compares the behavior of identical and fraternal twins to determine the influence of genes vs. environment.

• Example: Identical twins raised apart both develop similar phobias, suggesting a genetic influence.

Temperament Studies

Studies that examine the biological basis of personality traits from infancy.

• Example: Some infants are naturally more irritable or calm regardless of parenting style, indicating inborn temperament.

Adoption Studies

Studies that examine similarities between adopted children and their biological vs. adoptive parents.

• Example: An adopted child shares more traits with their biological parents than their adoptive ones, supporting genetic influence.

Nervous System

The body’s communication network that coordinates actions and transmits signals to and from different body parts.

• Example: When you touch a hot stove, your nervous system quickly sends a signal to your brain, prompting you to pull your hand away.

Spinal Cord

A long bundle of nerves that relays messages between the brain and the rest of the body.

• Example: A spinal cord injury can result in paralysis because the brain can no longer communicate with parts of the body below the injury.

Central Nervous System (CNS)

Consists of the brain and spinal cord; it processes and responds to sensory information.

• Example: When you hear music, your brain (part of the CNS) processes the sound and may trigger emotional responses.

Peripheral Nervous System (PNS)

All the nerves outside the brain and spinal cord; connects the CNS to limbs and organs.

• Example: The PNS sends signals from your fingers to your brain when you type on a keyboard.

Nerves

Bundles of axons that transmit signals throughout the body.

• Example: The optic nerve transmits visual information from the eye to the brain.

Somatic Nervous System

The part of the PNS that controls voluntary muscle movements.

• Example: You raise your hand in class to ask a question—controlled by the somatic nervous system.

Autonomic Nervous System

Controls involuntary body functions like heart rate, digestion, and breathing.

• Example: Your heart rate increases during a scary movie without you thinking about it.

Reflexes

Automatic responses to stimuli, processed through the spinal cord without brain input.

• Example: You instantly pull your hand away after touching something hot, even before you feel the pain.

Sensory Neurons (afferent)

Neurons that carry signals from sensory receptors to the CNS.

• Example: When you feel cold, sensory neurons send that information to your brain.

Motor Neurons

Neurons that transmit signals from the CNS to muscles, enabling movement. Y

• Example: Your brain sends a signal through motor neurons to move your hand away from a sharp object.

Sympathetic Nervous System

apPPart of the autonomic system that prepares the body for "fight or flight" in stressful situations.

• Example: Your pupils dilate, and heart rate increases when you're about to give a big speech.

Parasympathetic Nervous System

Part of the autonomic system that calms the body and conserves energy.

• Example: After a stressful event, your breathing slows and digestion resumes.

Interneurons

Neurons in the brain and spinal cord that connect sensory and motor neurons.

• Example: In a reflex, interneurons in the spinal cord quickly relay signals from sensory to motor neurons.

Gate Control Theory

Theory that the spinal cord contains a “gate” that blocks or allows pain signals to pass to the brain.

• Example: Rubbing your elbow after bumping it can reduce pain by “closing” the gate to pain signals.

Glial cell

Support cells in the nervous system that nourish, protect, and insulate neurons.

• Example: Glial cells form the myelin sheath around axons to speed up neural communication.

Cell body (Soma)

The main part of the neuron containing the nucleus; processes incoming signals.

• Example: After receiving signals from dendrites, the cell body decides whether to send the message along the axon.

Neurons

Nerve cells that transmit information throughout the body.

• Example: Neurons send pain signals from your foot to your brain when you step on a sharp object.

Dendrite

Branch-like extensions of a neuron that receive messages from other neurons.

• Example: Dendrites collect signals from neighboring neurons, like a phone receiver picking up calls.

Axon

The long extension of a neuron that carries messages away from the cell body.

• Example: The axon transmits a message to muscles telling your hand to move.

Myelin Sheath

A fatty layer that covers and insulates the axon, increasing the speed of neural impulses.

• Example: In multiple sclerosis, damage to the myelin sheath causes slow or disrupted neural communication.

Node of Ranvier

Gaps in the myelin sheath that help speed up neural transmission.

• Example: Electrical impulses “jump” from one node to the next, speeding communication in the neuron.

Axon terminal (terminal buttons)

The endpoint of an axon that releases neurotransmitters into the synapse.

• Example: When a message reaches the axon terminal, neurotransmitters like dopamine are released into the synaptic gap.

Reflex Arc

A neural pathway that controls a reflex, bypassing the brain for quick reactions.

• Example: You pull your hand away from a hot pan before the pain even reaches your brain.

Synapse

The gap between neurons where neurotransmitters are released.

• Example: Serotonin crosses the synapse to affect mood and emotional regulation.

Sensory Neurons (afferent)

Neurons that carry information from sensory receptors to the brain/spinal cord.

• Example: Sensory neurons transmit the feeling of cold from your fingers to your brain.

Motor Neurons (efferent)

Neurons that carry signals from the brain/spinal cord to muscles.

• Example: Your brain sends a signal via motor neurons to contract your leg muscle and kick a ball.

Interneurons

Neurons in the brain and spinal cord that connect sensory and motor neurons.

• Example: Interneurons relay pain signals from sensory to motor neurons so you quickly move away from danger.

All-or-nothing Principal

A neuron either fires completely or not at all—there’s no partial firing.

• Example: Like flipping a light switch, the neuron sends a full signal once the threshold is met.

Action Potential

A brief electrical charge that travels down the axon when a neuron fires.

• Example: When you touch something hot, an action potential carries that info from your hand to your brain.

Depolarization

The process where the inside of a neuron becomes more positive, starting the action potential.

• Example: Sodium ions rushing into the neuron cause depolarization, like opening floodgates.

Permeability

The ability of the neuron’s membrane to allow certain ions to pass through.

• Example: During an action potential, the membrane becomes permeable to sodium ions.

Refractory Period (Absolute and Relative)

Time after an action potential when a neuron can’t fire again (absolute) or can only fire with strong stimulation (relative).

• Example: After firing, a neuron needs time to reset before it can fire again, like waiting to reload a Nerf gun.

Resting Potential

The stable, negative charge of a neuron when it’s not firing.

• Example: Like a battery that’s fully charged but not in use, the neuron is ready but inactive.

Reuptake

The process by which neurotransmitters are reabsorbed by the sending neuron.

• Example: After serotonin is released into the synapse, it’s reabsorbed to be reused later.

Firing Threshold

The level of stimulation required for a neuron to fire.

• Example: If a stimulus is strong enough to meet the threshold, the neuron fires—like pressing hard enough on a doorbell.