AP Psychology Unit 1: Biological Bases of Behavior

Physiological psychology

The branch of psychology that studies the biological bases of behavior and mental processes.

Traits

Relatively stable characteristics or qualities that influence behavior across situations.

Evolutionary perspective

A psychological approach that explains behavior and mental processes in terms of natural selection and adaptation.

Heritability

A statistical measure of how much of the variation in a trait within a population is due to genetic differences.

Environmentality

The proportion of variation in a trait that is due to environmental factors rather than genetics.

Nature versus nurture debate

The ongoing question of how much of behavior and mental processes are shaped by genetics (nature) versus environment and experience (nurture).

Nervous system

The body's electrochemical communication network consisting of the brain, spinal cord, and all nerves.

Central nervous system (CNS)

The brain and spinal cord; the body's command center that processes and coordinates information.

Peripheral nervous system (PNS)

All nerves outside the brain and spinal cord that connect the CNS to the rest of the body.

Neurons

Specialized cells that transmit electrical and chemical signals throughout the nervous system.

Sensory (afferent) neurons

Neurons that carry information from sensory receptors toward the brain and spinal cord.

Motor (efferent) neurons

Neurons that carry commands from the brain and spinal cord to muscles and glands.

Reflexes

Automatic, involuntary responses to stimuli that occur without conscious thought.

Reflex arc

The neural pathway that controls a reflex action, typically involving a sensory neuron, interneuron, and motor neuron.

Interneurons

Neurons within the brain and spinal cord that connect sensory and motor neurons and process information.

Somatic nervous system

The division of the PNS that controls voluntary muscle movements and receives sensory information.

Autonomic nervous system

The division of the PNS that controls involuntary functions like heart rate, digestion, and breathing.

Sympathetic nervous system

The division of the autonomic nervous system that prepares the body for fight-or-flight responses.

Parasympathetic nervous system

The division of the autonomic nervous system that calms the body and restores it to a resting state.

Nerves

Bundles of axons that transmit signals between the CNS and the rest of the body.

Soma

The cell body of a neuron that contains the nucleus and keeps the cell alive.

Dendrites

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

Axon

The long fiber that extends from the soma and carries electrical impulses away from the cell body toward other neurons.

Myelin sheath

A fatty insulating layer that wraps around axons and speeds up the transmission of electrical signals.

Nodes of Ranvier

Gaps in the myelin sheath where the electrical signal is regenerated as it travels down the axon.

Terminal buttons

Small knobs at the end of axon branches that release neurotransmitters into the synapse.

Synapse

The tiny gap between the terminal button of one neuron and the dendrite or soma of the next neuron where chemical communication occurs.

Neurotransmitters

Chemical messengers that transmit signals across the synapse from one neuron to another.

Glial cells

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

Resting membrane potential

The electrical charge of a neuron when it is not firing, typically around -70 millivolts.

Nerve impulse (action potential)

The electrical signal that travels down the axon when a neuron fires, caused by a rapid change in membrane charge.

Depolarization

The process by which a neuron's membrane becomes less negative inside as it fires, triggering an action potential.

Refractory phase

The brief period after a neuron fires during which it cannot fire again, allowing time to reset.

Excitatory

Describes neurotransmitters or signals that increase the likelihood that a neuron will fire.

Inhibitory

Describes neurotransmitters or signals that decrease the likelihood that a neuron will fire.

Reuptake (neurotransmitters)

The process by which neurotransmitters are reabsorbed by the sending neuron after crossing the synapse.

Acetylcholine

A neurotransmitter involved in muscle movement, memory, and the autonomic nervous system.

Serotonin

A neurotransmitter that regulates mood, sleep, and appetite; low levels are linked to depression.

Dopamine

A neurotransmitter associated with reward, motivation, and movement; implicated in addiction and Parkinson's disease.

GABA

The main inhibitory neurotransmitter in the brain that reduces neural activity and promotes calm.

Glutamate

The main excitatory neurotransmitter in the brain involved in learning and memory.

Norepinephrine

A neurotransmitter and hormone involved in alertness, arousal, and the fight-or-flight response.

Endorphins

Natural pain-relieving neurotransmitters released during exercise, excitement, or injury.

Substance P

A neurotransmitter involved in transmitting pain signals to the brain.

Hormones

Chemical messengers released by glands into the bloodstream that regulate bodily functions and behavior.

Pituitary gland

The master gland of the endocrine system that controls other glands and releases hormones regulating growth and reproduction.

Epinephrine

A hormone (also called adrenaline) released by the adrenal glands during stress that prepares the body for fight or flight.

Norepinephrine (endocrine)

A hormone released by the adrenal glands alongside epinephrine during stress, contributing to arousal and alertness.

Leptin

A hormone produced by fat cells that signals the brain to reduce appetite and increase energy expenditure.

Ghrelin

A hormone produced by the stomach that signals hunger to the brain.

Melatonin

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

Oxytocin

A hormone and neurotransmitter associated with bonding, trust, and social connection; released during hugging and childbirth.

Agonist

A drug or chemical that mimics or enhances the effect of a neurotransmitter by binding to its receptor.

Antagonist

A drug or chemical that blocks or reduces the effect of a neurotransmitter by binding to its receptor without activating it.

Drugs

Chemicals that alter brain chemistry and behavior by affecting neurotransmitter systems.

Alcohol

A depressant drug that slows CNS activity by enhancing GABA and inhibiting glutamate.

Barbiturates

Depressant drugs that reduce anxiety and induce sleep by enhancing GABA activity.

Tranquilizers

Depressant drugs that reduce anxiety and produce calm by slowing CNS activity.

Caffeine

A stimulant drug that blocks adenosine receptors, increasing alertness and reducing fatigue.

Amphetamines

Stimulant drugs that increase dopamine and norepinephrine release, boosting energy and alertness.

Cocaine

A stimulant drug that blocks reuptake of dopamine, flooding the synapse and producing intense euphoria.

Nicotine

A stimulant drug in tobacco that mimics acetylcholine, increasing alertness and producing mild euphoria.

Opioids

Drugs that bind to endorphin receptors to relieve pain and produce euphoria; highly addictive.

Hallucinogens

Drugs that alter perception and produce hallucinations by disrupting normal neurotransmitter activity.

Dependence

A state in which a person needs a drug to function normally, experiencing withdrawal without it.

Tolerance

The need for increasing amounts of a drug to achieve the same effect due to the brain adapting to its presence.

Withdrawal

Physical and psychological symptoms that occur when a person stops using a drug they are dependent on.

Hindbrain

The lower region of the brain including the cerebellum, brainstem, and medulla that controls basic survival functions.

Cerebellum

A brain structure at the back of the hindbrain that coordinates voluntary movement, balance, and fine motor skills.

Brain stem

The stalk-like structure connecting the brain to the spinal cord that controls basic life functions like breathing and heart rate.

Medulla oblongata

The lower part of the brain stem that controls vital automatic functions including breathing, heart rate, and swallowing.

Reticular activating system (RAS)

A network of neurons in the brain stem that regulates arousal, alertness, and sleep-wake transitions.

Brain's reward system

A set of brain structures including the nucleus accumbens that release dopamine in response to pleasurable activities.

Pons

A brain stem structure that relays signals between the cerebellum and cortex and plays a role in sleep and dreaming.

Forebrain

The largest and most complex brain region including the cerebral cortex, thalamus, and limbic system.

Limbic system

A set of brain structures involved in emotion, memory, and motivation including the amygdala and hippocampus.

Thalamus

A brain structure that acts as a relay station, routing sensory information to the appropriate cortical areas.

Hippocampus

A brain structure in the limbic system critical for forming new long-term memories.

Anterograde amnesia

The inability to form new memories after brain damage, while memories before the damage remain intact.

Amygdala

A limbic system structure involved in processing emotions, especially fear and aggression.

Hypothalamus

A brain structure that regulates basic drives including hunger, thirst, body temperature, and sexual behavior, and controls the pituitary gland.

Lateral hypothalamus

A region of the hypothalamus associated with triggering hunger; stimulation causes eating.

Ventromedial hypothalamus

A region of the hypothalamus associated with signaling fullness and stopping eating.

Cerebral cortex

The outer layer of the brain responsible for higher-order processes including thinking, perceiving, and language.

Sensory cortex

The area of the cortex that receives and processes sensory information from the body.

Motor cortex

The area of the cortex that controls voluntary body movements.

Left and right cerebral hemispheres

The two halves of the cerebral cortex, each controlling the opposite side of the body and specialized for different functions.

Corpus callosum

The thick band of nerve fibers connecting the left and right cerebral hemispheres, allowing communication between them.

Expressive aphasia (Broca's area)

A language disorder caused by damage to Broca's area in the left frontal lobe, resulting in difficulty producing speech.

Receptive aphasia (Wernicke's area)

A language disorder caused by damage to Wernicke's area in the left temporal lobe, resulting in difficulty understanding language.

Split-brain patients

Individuals whose corpus callosum has been severed, causing the two hemispheres to function independently.

Cortex components - Frontal lobe

The front section of the cerebral cortex involved in planning, decision-making, impulse control, and voluntary movement.

Cortex components - Parietal lobe

The upper back section of the cerebral cortex that processes sensory information including touch and spatial awareness.

Cortex components - Temporal lobe

The side section of the cerebral cortex involved in hearing, language comprehension, and memory.

Cortex components - Occipital lobe

The back section of the cerebral cortex that processes visual information.

Association areas

Regions of the cortex that integrate information from multiple sensory and motor areas to support complex thinking.

Apraxia

The inability to perform purposeful movements despite having intact motor and sensory function.

Agnosia

The inability to recognize objects, faces, or sounds despite intact sensory function.

Alexia

The inability to read despite normal vision, caused by brain damage.

Agraphia

The inability to write despite normal hand function, caused by brain damage.