AP Psychology Unit 1: Biological Bases of Behavior

Comprehensive vocabulary flashcards covering key topics, structures, and physiological mechanisms from Unit 1: Biological Bases of Behavior.

Heredity (Nature)

The genetic transfer of biological and behavioral characteristics from biological parents to their offspring.

Environment (Nurture)

Every external, non-genetic influence surrounding an individual, encompassing prenatal conditions through lifelong social and physical experiences.

Genetic Predisposition

An increased genetic likelihood or vulnerability of developing a particular disease or behavioral trait under specific environmental conditions.

Natural Selection

The evolutionary principle that inherited biological or behavioral variations contributing to survival and reproduction are most likely to be passed on to future generations.

Twin Studies

Behavioral genetics research comparing identical (monozygotic) and fraternal (dizygotic) twins to estimate the relative influence of genes versus environment.

Adoption Studies

Research evaluating adoptees relative to their biological and adoptive parents to disentangle genetic influences from environmental rearing influences.

Central Nervous System (CNS)

The division of the nervous system comprising the brain and the spinal cord, responsible for processing sensory input and coordinating bodily activity.

Peripheral Nervous System (PNS)

The sensory and motor neurons connecting the central nervous system to the rest of the body, including limbs and internal organs.

Somatic Nervous System

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

Autonomic Nervous System

The division of the peripheral nervous system regulating involuntary bodily functions such as heart rate, digestion, and respiratory rate.

Sympathetic Nervous System

The branch of the autonomic nervous system that arouses the body and mobilizes energy in stressful situations, initiating the 'fight-or-flight' response.

Parasympathetic Nervous System

The branch of the autonomic nervous system that calms the body and conserves energy, mediating the 'rest-and-digest' state.

Glial Cells

Non-neuronal support cells in the nervous system that nourish, protect, insulate (via myelin), and maintain homeostasis for neurons.

Reflex Arc

A simple neural pathway mediating an automatic, involuntary response to a stimulus, typically operating through the spinal cord before sensory signals reach the brain.

Sensory Neurons

Afferent neurons that carry incoming sensory information from sensory receptors toward the central nervous system.

Motor Neurons

Efferent neurons that carry outgoing instructions from the central nervous system to muscles and glands.

Interneurons

Neurons located entirely within the brain and spinal cord that communicate internally and process information between sensory inputs and motor outputs.

All-or-Nothing Principle

The physiological rule stating that a neuron fires completely with an action potential of full strength or does not fire at all once threshold is reached.

Depolarization

A reduction in electrical charge difference across the neural membrane as positive ions (such as sodium) rush into the cell, triggering an action potential.

Refractory Period

The brief recovery phase following an action potential during which a neuron cannot fire another action potential until resting potential is restored.

Resting Potential

The stable negative electrical charge of a neuron's interior relative to its exterior when the cell is inactive, typically around $-70\,\text{mV}$.

Threshold

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

Reuptake

The process by which excess neurotransmitters released into the synaptic cleft are reabsorbed by the presynaptic neuron.

Dopamine

A neurotransmitter regulating motor movement, motivation, pleasure, reward pathways, and attention; implicated in Parkinson's disease and schizophrenia.

Serotonin

A neurotransmitter regulating mood, hunger, sleep, and emotional arousal; deficits are commonly associated with clinical depression.

GABA (Gamma-Aminobutyric Acid)

The primary inhibitory neurotransmitter in the central nervous system, serving to calm neural activity and prevent overexcitation.

Glutamate

The primary excitatory neurotransmitter in the central nervous system, involved in synaptic plasticity, learning, and memory.

Acetylcholine (ACh)

A neurotransmitter essential for muscle contraction, voluntary motor control, attention, and memory formation; linked to Alzheimer's disease.

Endorphins

Endogenous opioid neurochemicals released in response to pain or vigorous physical exercise to elevate mood and blunt pain perception.

Agonist

A molecule or drug that binds to a neurotransmitter receptor site and mimics or increases the action of that neurotransmitter.

Antagonist

A molecule or drug that binds to a receptor site and inhibits or blocks the normal action of a neurotransmitter.

Tolerance

The diminished physiological or behavioral response to a psychoactive drug resulting from repeated use, necessitating larger doses to achieve the desired effect.

Medulla

The base structure of the brainstem that controls essential autonomic, life-sustaining functions such as heartbeat and respiration.

Reticular Activating System (RAS)

A nerve network within the brainstem that plays a central role in regulating arousal, alertness, and the sleep/wake transition.

Cerebellum

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

Thalamus

The brain's primary sensory switchboard, directing sensory information (except smell) to relevant sensory processing regions of the cerebral cortex.

Hypothalamus

A limbic structure below the thalamus directing maintenance activities (hunger, thirst, body temperature), governing the endocrine system via the pituitary gland, and linked to reward.

Hippocampus

A neural center located in the limbic system essential for processing and consolidating new explicit, declarative memories for long-term storage.

Amygdala

Two almond-shaped neural clusters in the limbic system critically involved in emotional processing, particularly fear and aggression.

Corpus Callosum

The broad band of axon fibers connecting the left and right cerebral hemispheres, enabling interhemispheric communication.

Frontal Lobes

The portion of the cerebral cortex lying behind the forehead, involved in speaking, muscle movements, decision-making, planning, and judgment.

Parietal Lobes

The portion of the cerebral cortex lying at the top rear of the head that receives and processes sensory inputs for touch and spatial body positioning.

Occipital Lobes

The portion of the cerebral cortex at the back of the head containing the primary visual cortex, responsible for processing visual sensory inputs.

Temporal Lobes

The portion of the cerebral cortex lying roughly above the ears containing the primary auditory cortex, vital for hearing, language comprehension, and face recognition.

Broca's Area

A specialized region usually located in the left frontal lobe that controls the motor movements involved in speech production.

Wernicke's Area

A specialized region typically located in the left temporal lobe that is essential for language comprehension and meaningful expression.

Contralateral Organization

The structural arrangement of the nervous system wherein each cerebral hemisphere receives sensory inputs from and controls motor output for the opposite side of the body.

Brain Plasticity

The brain's ability to reorganize neural pathways and adapt structurally or functionally in response to experience, learning, or injury.

Circadian Rhythm

An internal biological clock running on an approximate 24-hour cycle that regulates body temperature, hormone release, and the sleep-wake pattern.

REM Sleep (Paradoxical Sleep)

A recurring sleep stage characterized by rapid eye movements, vivid dreaming, increased brain activity, and temporary muscular paralysis.

REM Rebound

The significant increase in the frequency and duration of REM sleep episodes following periods of intentional or unintentional sleep deprivation.

Activation-Synthesis Theory

The neurobiological theory proposing that dreams are the cerebral cortex's subjective attempt to synthesize and make sense of random neural activity originating in the brainstem.

Insomnia

A persistent sleep disorder characterized by chronic difficulty falling asleep or staying asleep, resulting in daytime impairment.

Narcolepsy

A neurological sleep disorder marked by uncontrollable sleep attacks, sudden drowsiness, and lapses directly into REM sleep at inappropriate times.

Sleep Apnea

A sleep disorder characterized by repeated temporary cessations of breathing during sleep and subsequent momentary awakenings.

Transduction

The conversion of external environmental physical energy (such as light waves or sound waves) into neural impulses that the central nervous system can interpret.

Absolute Threshold

The minimum stimulus intensity required to detect a particular physical stimulus at least $50\%$ of the time.

Just-Noticeable Difference (JND)

The minimum physical difference between two stimuli required for an observer to detect that they are not identical $50\%$ of the time; also termed the difference threshold.

Weber's Law

The sensory principle stating that to perceive a difference between two stimuli, they must differ by a constant minimum percentage rather than a constant physical amount.

Sensory Adaptation

The diminishing neural responsiveness and perceptual sensitivity that occurs following prolonged, unchanging exposure to a sensory stimulus.

Rods

Retinal photoreceptors concentrated in the periphery that detect black, white, and shades of gray, crucial for peripheral vision and dim-light night vision.

Cones

Retinal photoreceptors clustered near the fovea that function best in daylight or well-lit environments, mediating fine detail and color sensation.

Trichromatic Theory

The Young-Helmholtz theory asserting that the retina contains three distinct types of color receptors sensitive to red, green, or blue wavelengths.

Opponent-Process Theory

The theory that color vision is enabled by opposing retinal ganglion processes (red-green, blue-yellow, and black-white), explaining afterimages.

Prosopagnosia

A neurological condition marked by the inability to recognize familiar human faces, often caused by damage to the fusiform face area, while general visual acuity remains intact.

Place Theory

In hearing, the theory linking pitch perception to the specific physical location where the basilar membrane is stimulated by sound vibrations.

Frequency Theory

In hearing, the theory stating that the rate of nerve impulses traveling up the auditory nerve matches the frequency of the sound tone, enabling low-pitch perception.

Sensorineural Deafness

Hearing loss caused by mechanical damage to the cochlea's hair cell receptor cells or to the auditory nerve pathways; also called nerve deafness.

Gate Control Theory

The theory proposing that a neurological 'gate' in the spinal cord either blocks pain signals or allows them to ascend to the brain via small versus large nerve fiber activation.

Vestibular Sense

The sensory system monitoring body orientation, head position, and balance, mediated by fluid-filled semicircular canals and vestibular sacs inside the inner ear.

Kinesthesis

The sensory system enabling awareness of the position, motion, and coordination of individual body parts via receptors in tendons, joints, and muscles.