AP Psychology - Unit 1: Biological Bases of Behavior

Nature

The influence of genetic and biological factors on human development and behavior.

Evolutionary Perspective

A branch of psychology that studies how natural selection and evolutionary principles explain human behavior and mental processes.

Natural Selection

The principle that inherited traits contributing to survival and reproduction are more likely to be passed on to future generations.

Environment

Every non-genetic, external influence that shapes an individual, ranging from prenatal nutrition to social culture.

Heredity

The genetic transmission of characteristics and physical traits from parents to offspring.

Genes

The biochemical units of heredity that make up chromosomes and contain instructions for synthesizing proteins.

Genome

The complete set of genetic instructions and DNA sequences present in an organism.

Nurture

The environmental, social, and experiential influences that shape an individual's development.

Eugenics

The controversial movement advocating for the improvement of human genetic qualities through selective breeding.

Twin studies

Research designs comparing identical and fraternal twins to estimate the relative contribution of genetics versus environment.

Adoption Studies

Research comparing adopted children to their biological and adoptive parents to evaluate genetic versus environmental influences.

Identical (Monozygotic) Twins

Twins who develop from a single fertilized egg that splits in two, creating genetically identical individuals.

Fraternal (Dizygotic) twins

Twins who develop from separate fertilized eggs, sharing approximately 50% of their genes like typical siblings.

Epigenetics

The study of environmental influences on gene expression that occur without altering the underlying DNA sequence.

Nervous System

The body's speedy, electrochemical communication network, divided into the central and peripheral systems.

Central Nervous System (CNS)

The complex of nerve tissues consisting of the brain and spinal cord, which processes information and coordinates activity.

Nerves

Bundled axons forming neural cables that connect the central nervous system with muscles, glands, and sense organs.

Reflex

An automatic, unlearned response to a sensory stimulus, governed by simple spinal cord pathways.

Autonomic Nervous System (ANS)

The division of the peripheral nervous system that controls involuntary bodily functions like heart rate and digestion.

Sympathetic Nervous System

The branch of the autonomic nervous system that arouses the body, mobilizing energy during "fight-or-flight" situations.

Peripheral Nervous System (PNS)

The sensory and motor neurons connecting the central nervous system to the rest of the body.

Somatic Nervous System

The division of the peripheral nervous system controlling voluntary movements of skeletal muscles.

Parasympathetic Nervous System

The branch of the autonomic nervous system that calms the body, conserving energy in "rest-and-digest" states.

Neurons

Individual nerve cells that form the basic building blocks of the nervous system.

Cell Body

The part of a neuron containing the nucleus, responsible for maintaining life functions and integrating incoming signals (also called the soma).

Dendrites

Branching extensions of a neuron that receive chemical messages from other cells and conduct impulses toward the cell body.

Axon

The long extension of a neuron that transmits electrical impulses away from the cell body toward other neurons or muscles.

Myelin

A fatty layer wrapping around many neuronal axons that insulates them and speeds up signal transmission.

Synapse

The microscopic junction between the axon terminal of a sending neuron and the dendrite or cell body of a receiving neuron.

Glial Cells

Non-neuronal cells in the nervous system that support, nourish, protect, and insulate neurons.

Reflex Arc

The basic neural pathway controlling a reflex, typically consisting of a sensory receptor, sensory neuron, interneuron, motor neuron, and effector.

Sensory Neurons

Neurons that carry incoming information from sensory receptors toward the brain and spinal cord (afferent neurons).

Motor Neurons

Neurons that carry outgoing instructions from the brain and spinal cord to muscles and glands (efferent neurons).

Interneurons

Neurons within the central nervous system that communicate internally and process information between sensory inputs and motor outputs.

Action Potential

A brief electrical charge or nerve impulse that travels down an axon when a neuron fires.

All-or-Nothing Principle

The rule that a neuron fires completely or not at all; an action potential always maintains the same strength once triggered.

Depolarization

The shift in a neuron's membrane potential toward a positive charge, moving it closer to generating an action potential.

Reuptake

The process by which a sending neuron reabsorbs excess neurotransmitter molecules left in the synaptic cleft.

Refractory Period

A brief resting pause after a neuron fires during which another action potential cannot be triggered.

Resting Potential

The stable, negative electrical charge across a neuron's membrane when it is inactive and not sending a signal.

Threshold

The minimum level of stimulation required to trigger an action potential in a neuron.

Myasthenia Gravis

A neuromuscular autoimmune disorder characterized by weakness and rapid fatigue of voluntary muscles due to impaired acetylcholine receptors.

Multiple Sclerosis

A progressive autoimmune disease where the immune system destroys the myelin sheath of central nervous system axons, disrupting communication.

Neurotransmitters

Chemical messengers released by neurons across the synaptic gap to transmit signals to target cells.

Excitatory Neurotransmitters

Neurotransmitters that depolarize the postsynaptic membrane, increasing the likelihood that the receiving neuron will fire an action potential.

Dopamine

A key neurotransmitter influencing movement, learning, attention, emotion, and the brain's reward system.

Norepinephrine

A neurotransmitter involved in arousal, alertness, and the body's response to stress.

GABA

The primary inhibitory neurotransmitter in the brain, functioning to reduce neuronal excitability.

Substance P

A neurotransmitter involved in transmitting pain signals from the peripheral nervous system to the central nervous system.

Hormones

Chemical messengers produced by endocrine glands that travel through the bloodstream to affect targeted tissues and organs.

Leptin

A protein hormone produced by adipose (fat) cells that acts on the hypothalamus to suppress appetite and signal satiety.

Melatonin

A hormone secreted by the pineal gland that regulates sleep-wake cycles in response to darkness.

Inhibitory Neurotransmitters

Neurotransmitters that hyperpolarize the postsynaptic membrane, decreasing the likelihood that the receiving neuron will fire.

Seretonin

A neurotransmitter regulating mood, hunger, sleep, and emotional stability.

Glutamate

The primary excitatory neurotransmitter in the brain, heavily involved in learning and memory formation.

Endorphins

Endogenous opiate-like neurotransmitters that diminish pain perception and enhance feelings of pleasure.

Acetylcholine

A neurotransmitter enabling muscle action, learning, and memory; degraded in Alzheimer's disease.

Endocrine system

The body's "slow" chemical communication system consisting of glands that secrete hormones directly into the bloodstream.

Adrenaline

A hormone and neurotransmitter (epinephrine) released during stress that increases heart rate, blood pressure, and energy supply.

Ghrelin

A hormone secreted by an empty stomach that signals hunger to the hypothalamus.

Oxytocin

A hormone released by the pituitary gland that promotes social bonding, trust, empathy, and labor contractions.

Psychoactive drugs

Chemical substances that alter perceptions, mood, consciousness, or behavior by acting on neurotransmitter systems.

Substance use disorder

A medical condition characterized by continued, compulsive drug craving and use despite significant adverse consequences.

Antagonist

A chemical agent or drug that blocks or inhibits the normal action of a specific neurotransmitter.

Stimulants

A class of psychoactive drugs that excite neural activity and speed up bodily functions.

Caffeine

A widely used central nervous system stimulant that boosts alertness by blocking adenosine receptors.

Cocaine

A powerful, addictive stimulant derived from the coca plant that blocks dopamine reuptake, producing intense euphoria.

Methamphetamines

A highly addictive synthetic stimulant that triggers massive dopamine release, elevating energy and mood while damaging neural pathways.

Ecstasy

A synthetic drug (MDMA) acting as both a stimulant and mild hallucinogen, increasing serotonin, dopamine, and oxytocin to enhance mood and social empathy.

Opioids

Pain-relieving drugs that bind to endorphin receptors, suppressing central nervous system activity and pain perception.

Heroin

An illicit, highly addictive opioid drug that mimics endorphins, inducing rapid euphoria and respiratory depression.

Addiction

Compulsive craving and involvement in a behavior or substance despite negative physical, psychological, or social outcomes.

Agonist

A chemical agent or drug that binds to and activates a receptor, mimicking the effect of a natural neurotransmitter.

Reuptake Inhibitor

A drug that blocks sending neurons from reabsorbing neurotransmitters, increasing their concentration in the synaptic gap.

Depressants

A class of psychoactive drugs that calm neural activity and slow down bodily processes.

Alcohol

A widely consumed depressant that enhances GABA activity and inhibits glutamate, impairing judgment, motor control, and memory.

Hallucinogens

Psychedelic drugs that distort perceptions and evoke sensory experiences in the absence of real sensory input.

Marijuana

A plant product containing THC that produces altered sensory perceptions, relaxation, and mild hallucinations.

LSD

A powerful synthetic hallucinogen that produces vivid visual hallucinations and altered time perception by acting on serotonin pathways.

Tolerance

The diminished effect experienced after repeated use of a drug, requiring larger doses to achieve the same state.

Withdrawal

The cluster of distressing physical and psychological symptoms experienced when an addictive substance is suddenly discontinued.

Brain Plasticity (neuroplasticity)

The brain's ability to reorganize itself by forming new neural pathways, especially following injury or during learning.

EEG

Electroencephalogram; an imaging technique that records electrical waves flowing across the brain's surface using electrodes placed on the scalp.

MEG

Magnetoencephalography; a brain imaging technique measuring subtle magnetic fields produced by brain electrical activity.

MRI

Magnetic Resonance Imaging; a technique using magnetic fields and radio waves to produce high-resolution structural images of brain anatomy.

CT

Computed Tomography; a series of X-ray photographs taken from different angles and combined into cross-sectional images of internal brain structures.

PET

Positron Emission Tomography; a functional imaging technique tracking radioactive glucose consumption to reveal active brain regions.

fMRI

Functional Magnetic Resonance Imaging; a technique revealing blood flow and brain activity by comparing successive MRI scans.

Lesions

Surgical or pathological damage to tissue, used in neuroscience to study functional loss after brain injury.

Brain Stem

The oldest and central core of the brain, beginning where the spinal cord swells; responsible for automatic survival functions.

Hindbrain

The lower posterior portion of the brain containing the medulla, pons, and cerebellum, regulating basic bodily operations.

Midbrain

A small region between the hindbrain and forebrain involved in integrating sensory signals and coordinating auditory/visual reflexes.

Forbrain

The largest and most complex brain division, containing the cerebral cortex, thalamus, hypothalamus, and limbic system.

Medulla Oblongata

The base of the brainstem that controls vital involuntary functions such as heartbeat, breathing, and blood pressure.

Reticular Activatiing System (Reticular Formation)

A nerve network extending through the brainstem that plays a critical role in controlling arousal and alertness.

Cerebellum

The "little brain" at the rear of the brainstem, responsible for coordinating voluntary movement, balance, and procedural memory.

Cerebral Cortex

The intricate fabric of interconnected neural cells covering the cerebral hemispheres, responsible for ultimate control and information processing.

Limbic System

A neural structure network (including hippocampus, amygdala, and hypothalamus) associated with emotions, drives, and memory.

Thalamus

The brain's sensory control center located atop the brainstem, directing incoming sensory messages to the cortex (except smell).

Hypothalamus

A limbic structure lying below the thalamus that directs eating, drinking, body temperature, and governs the endocrine system via the pituitary gland.