Unit 1 Biological Bases of Behavior

heredity

Passing of traits from parents to offspring

nature

The influence of our inherited, genetic characteristics on our personality, physical growth, intellectual growth, and social interactions.

nurture

The influence of external, environmental factors (such as family, culture, education, and experiences) on development.

Genetic predisposition

An inherited genetic pattern that makes one more susceptible to developing a certain disease or behavior.

evolutionary perspective of psychology

Explores how natural selection of traits has promoted the survival of genes, affecting behavior and mental processes.

natural selection

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

eugenics

The controversial study of factors that influence the hereditary qualities of the human race and ways to "improve" those qualities, often through selective breeding.

twin studies

Used to study nature vs. nurture by comparing the similarity of monozygotic (identical) twins to dizygotic (fraternal) twins on a specific trait.

family studies

Researchers assess hereditary influence by examining blood relatives to see how much they resemble one another on a specific trait.

adoption studies

Assesses hereditary influence by comparing the traits of adopted children to both their biological parents (nature) and their adoptive parents (nurture).

central nervous system (CNS)

The brain and spinal cord

peripheral nervous system (PNS)

The sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

Autonomic nervous system

The part of the PNS that controls involuntary glands and muscles of internal organs (e.g., heart rate, digestion).

sympathetic nervous system

The "fight” or upping response that prepares the body

parasympathetic nervous system

The "rest” response that relaxes the body

somatic nervous system

The division of the peripheral nervous system that controls the body's skeletal muscles; governs voluntary movements.

neurons

The basic building blocks of the nervous system; nerve cells that receive, integrate, and transmit information via electrochemical signals.

Glial cells

Cells in the nervous system that support, nourish, and protect neurons; they also produce the myelin sheath.

reflex arc

A simple, automatic response to a sensory stimulus (like the knee

sensory neurons

Neurons that carry incoming information from the body's tissues and sensory receptors to the central nervous system (brain and spinal cord).

motor neurons

Neurons that carry outgoing information from the central nervous system (brain and spinal cord) to the muscles and glands.

interneurons

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

neural transmission

The process of electrochemical communication within and between neurons.

action potential

A neural impulse; a brief electrical charge (a depolarization) that travels down an axon.

all-or-nothing principle

The neuron fires entirely or not at all, meaning that it either transmits a signal at full strength or does not transmit it at all.

depolarization

The loss of the inside/outside charge difference in a neuron (going from negative to positive) when positive sodium ions flow into the axon, causing the action potential.

refractory period

A brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state.

reuptake

A neurotransmitter's reabsorption by the sending neuron after it has completed its work in the synapse.

neural threshold

The minimum level of stimulation required to trigger a neural impulse (action potential).

multiple sclerosis

An autoimmune disease resulting from the degeneration of the myelin sheath, leading to slowed or disrupted neural communication.

Myasthenia gravis

An autoimmune disease that impacts the neuromuscular junction, often by blocking acetylcholine (ACh) receptors, causing muscle weakness.

excitatory neurotransmitters

Neurotransmitters that bind to receptor sites and increase the likelihood that the receiving neuron will fire an action potential.

inhibitory neurotransmitters

Neurotransmitters that bind to receptor sites and decrease the likelihood that the receiving neuron will fire an action potential.

dopamine

A neurotransmitter linked to movement, learning, attention, emotion, and the brain's pleasure/reward system.

Serotonin

Affects mood, hunger, sleep, and arousal. (Undersupply linked to depression).

Norepinephrine

A neurotransmitter (and hormone) involved in alertness, arousal, and mood; associated with the "fight

Glutamate

The primary excitatory neurotransmitter in the CNS, playing a key role in synaptic transmission and neuronal communication. It is involved in various brain functions, including learning, memory, and neural plasticity.

GABA

Primary inhibitory neurotransmitter in the central nervous system. It promotes relaxation and reduces anxiety.

Endorphins

Natural pain relievers produced by the body; they also promote feelings of pleasure and euphoria. Released in response to stress, pain, or intense physical activity, such as exercise or excitement.

Substance P

A neurotransmitter that is involved in the transmission of pain messages to the brain.

Acetylcholine 

A neurotransmitter that enables muscle action and contraction, learning, and memory.  It is also involved in regulating the sleep-wake cycle and attention.

Hormones

Chemical messengers produced by glands in the endocrine system that travel through the bloodstream to target cells or organs, where they regulate various physiological processes and behaviors.

Adrenaline (Epinephrine)

Hormone secreted by the adrenal glands during stress; increases heart rate, blood pressure, and blood sugar, providing a surge of energy (fight or flight response) and prepares the body for immediate physical activity.

Leptin

Hormone secreted by fat cells; signals the hypothalamus to reduce appetite and increase metabolism (signals satiety).

Ghrelin

Hormone secreted by an empty stomach; sends "I'm hungry" signals to the brain (triggers hunger).

Melatonin

A hormone manufactured by the pineal gland that produces sleepiness, regulating the circadian rhythm.

Oxytocin

Hormone released by the pituitary gland; linked to social bonding, trust. Also for childbirth.

Psychoactive Drugs

Chemicals that affect the nervous system and result in altered consciousness, mood, or perception.

Agonist

A molecule (drug) that binds to a receptor site and mimics a neurotransmitter's effect, stimulating a response.

Antagonist

A molecule (drug) that binds to a receptor site and blocks or inhibits a neurotransmitter's action.

Reuptake inhibitors

Drugs (like SSRIs) that interfere with the reuptake of neurotransmitters, leaving more of the neurotransmitter in the synapse.

Stimulants

Drugs (e.g., caffeine, cocaine, amphetamines) that excite neural activity and speed up body functions.

Caffeine

A mild stimulant that increases alertness and wakefulness, primarily by blocking adenosine.

Cocaine

A powerful stimulant that produces temporary alertness and euphoria by blocking the reuptake of dopamine, norepinephrine, and serotonin.

Depressants

Drugs (e.g., alcohol, opioids, barbiturates) that reduce neural activity and slow body functions.

Alcohol

A depressant that slows neural processing (impairing judgment, motor skills) and disrupts memory formation; enhances the effects of GABA.

Hallucinogens

Psychedelic drugs (e.g., LSD, psilocybin) that distort perceptions and evoke sensory images in the absence of sensory input.

Marijuana

A psychoactive drug (mild hallucinogen) with the active ingredient THC; effects include euphoria, relaxation, and sensory distortion.

Opioids

Depressants that mimic endorphins (agonist), reducing pain and producing euphoria (e.g., heroin, morphine, fentanyl).

Heroin

A highly addictive narcotic drug (an opioid) derived from opium.

Tolerance

The diminishing effect with regular use of the same dose of a drug, requiring the user to take larger doses to experience the drug's effect.

Addiction

Compulsive drug craving and use, despite adverse consequences and often physical symptoms of withdrawal.

withdrawal

The discomfort and distress (physical and psychological) that follow discontinuing the use of an addictive drug.

Brain Stem

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

Medulla

The base of the brainstem; controls vital automatic functions like heartbeat and breathing.

Reticular Formation (Reticular Activating System)

A nerve network in the brainstem that plays a key role in controlling arousal, wakefulness, and filtering incoming stimuli.

Reward Center

A region in the limbic system (near the hypothalamus) associated with motivation, pleasure, and reward; rich in dopamine.

Cerebellum

The "little brain" at the rear of the brainstem; coordinates voluntary movement, balance, and procedural (nonverbal) memory.

Cerebral Cortex

The intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body's ultimate control and information processing center.

Limbic System

A set of brain structures involved in emotions, behavior, and long-term memory; it includes the hippocampus and amygdala.

Thalamus

The brain's sensory control center (switchboard), located on top of the brainstem; directs all sensory messages (except smell) to the cortex.

Hypothalamus

A neural structure lying below the thalamus; it directs maintenance activities (eating, drinking, body temperature), governs the endocrine system via the pituitary gland, and is linked to emotion and reward. (The 4 Fs).

Pituitary Gland

The "master gland" of the endocrine system; controlled by the hypothalamus, it regulates growth and controls other endocrine glands.

Hippocampus

A neural center located in the limbic system that helps process and store new explicit (conscious) memories.

Amygdala

bean-shaped clusters of neurons in the limbic system, involved in emotion regulation, especially fear and aggression, and processing emotional memories.

Corpus callosum

The large band of neural fibers connecting the two brain hemispheres and carrying messages between them.

Occipital lobes

Portion of the cerebral cortex at the back of the head; includes areas that receive and process information from the visual fields.

temporal lobes

Portion of the cerebral cortex lying roughly above the ears; includes the auditory areas and (typically in the left) Wernicke's area.

parietal lobes

Portion of the cerebral cortex at the top of the head; receives sensory input for touch and body position (contains the somatosensory cortex).

association areas

Areas of the cerebral cortex not involved in primary motor or sensory functions; they are involved in higher mental functions such as learning, remembering, thinking, and speaking.

somatosensory cortex

An area at the front of the parietal lobes that registers and processes body touch and movement sensations.

frontal lobes

Portion of the cerebral cortex behind the forehead; involved in speaking, muscle movements, planning, and judgment (contains motor cortex, Broca's area, prefrontal cortex).

linguistic processing

The cognitive processes involved in understanding and producing language (involves Broca's and Wernicke's areas).

higher-order thinking

A level of thinking that requires the student to think critically. It involves the ability to apply knowledge to new situations, analyze information, and create new ideas or solutions.

executive functioning

The cognitive abilities (planning, inhibition, working memory) that allow humans to plan, monitor, and control their thoughts and actions.

prefrontal cortex

The forward part of the brain that is crucial for higher-order thinking, decision-making, and regulating social behavior.

motor cortex

An area at the rear of the frontal lobes that controls voluntary movements.

split brain research

Studies of patients with a severed corpus callosum, revealing the independent functions and specialization of the two brain hemispheres.

hemispheric specialization (Lateralization)

The tendency for each brain hemisphere to excel at different functions (e.g., left for language, right for spatial/perceptual).

Broca's area

An area (usually in the left frontal lobe) that controls language expression by directing the muscle movements involved in speech.

Wernicke's area

An area (usually in the left temporal lobe) involved in language comprehension and reception.

Aphasia

Impairment of language, usually caused by left hemisphere damage either to Broca's area (impairing speaking) or to Wernicke's area (impairing understanding).

Contralateral hemispheric organization

The principle that the left side of the brain controls the right side of the body, and the right side of the brain controls the left side of the body.

Plasticity

The brain's ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.

EEG (Electroencephalogram)

An amplified recording of the waves of electrical activity sweeping across the brain's surface; measured by electrodes on the scalp (good for sleep studies).

fMRI (functional MRI)

A technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans (shows function and structure).

Lesioning

The removal or destruction of part of the brain (naturally or experimentally) to study its function.

Consciousness

Our subjective awareness of ourselves and our environment.

circadian rhythm

The biological clock; regular bodily rhythms (e.g., temperature, wakefulness) that occur on a 24

Jet lag

A disruption of circadian rhythms caused by crossing time zones.