AP Psychology Unit 1 PART A (Modules 1.1 to 1.4c) Biological Bases of Behavior

nature–nurture issue

the longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors. Today’s science views traits and behaviors as arising from the interaction of nature and nurture.

natural selection

the principle that the inherited traits enabling an organism to survive and reproduce in a particular environment will (in competition with other trait variations) most likely be passed on to succeeding generations.

evolutionary psychology

the study of the evolution of behavior and the mind, using principles of natural selection.

behavior genetics

the study of the relative power and limits of genetic and environmental influences on behavior.

eugenics

study of how to arrange reproduction within a human population to increase heritable characteristics regarded as desirable (basically racist; ex; aryans are the superior race)

identical (monozygotic) twins

individuals who developed from a single fertilized egg that split in two, creating two genetically identical organisms.

fraternal (dizygotic) twins

individuals who developed from separate fertilized eggs. They are genetically no closer than ordinary siblings, but they shared a prenatal environment.

mutation

a random error in gene replication that leads to a change.

environment

every nongenetic influence, from prenatal nutrition to our experiences of the people and things around us.

heredity

the genetic transfer of characteristics from parents to offspring.

genes

the biochemical units of heredity.

genome

the complete instructions for making an organism.

interaction

the interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity).

epigenetics

“above” or “in addition to” (epi) genetics; the study of the molecular mechanisms by which environments can influence genetic expression (without a DNA change).

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.

somatic nervous system

the division of the peripheral nervous system that controls the body’s skeletal muscles. Also called the skeletal nervous system.

autonomic [aw-tuh-NAHM-ik] nervous system (ANS)

the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.

sympathetic nervous system

the division of the autonomic nervous system that arouses the body, mobilizing its energy.

parasympathetic nervous system

the division of the autonomic nervous system that calms the body, conserving its energy.

nervous system

the body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems.

glial cells (glia)

cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory.

neurons

a nerve cell; the basic building block of the nervous system.

sensory (afferent) neurons

neurons that carry incoming information from the body’s tissues and sensory receptors to the brain and spinal cord.

motor (efferent) neurons

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.

interneurons

neurons within the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs.

reflex arc

a simple, automatic response to a sensory stimulus, such as the knee-jerk reflex.

nerves

bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sensory organs.

all-or-none response

a neuron’s reaction of either firing (with a full-strength response) or not firing.

action potential

a neural impulse; a brief electrical charge that travels down an axon.

depolarization

the process where a neuron’s membrane potential becomes less negative (more positive) essentially moving closer to firing an action potential

refractory period

in neural processing, 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.

firing threshold

the level of stimulation required to trigger a neural impulse.

multiple sclerosis

a chronic autoimmune disease that affects the central nervous system including the brain and spinal cord. may lose ability to see clearly, write, speak or walk

myasthenia gravis

chronic autoimmune disorder where antibodies destroy communication between nerves and muscles; causes weakness in the muscles of the body; double vision and unsteady movement

dopamine

activates the pleasure-reward center of the brain, coordination of body movement, and alertness; undersupply=parkinson’s disease, oversupply=schizophrenia

serotonin

well-being contentment, regulate hunger (specific foods can trigger), helps sleep cycle; lack = clinical depression

norepinephrine

fight or flight response, alertness and take action in times of danger; increases heart rate + blood pressure

glutamate

helps with memory and creating nerve connections; most common neurotransmitter

GABA

creates a sense of calm, anti-anxiety molecule; undersupply=seizures, insomnia

endorphins

pain control; works similarly to depressant drugs like opioids and heroin

acetylcholine (ACh)

activates voluntary muscle movement, learning and memory; lack = alzheimer’s disease

substance P

involved with perception of pain, released by sensory neurons; oversupply = chronic pain

adrenaline (hormone)

same as epinephrine; fight or flight response; adrenaline rush; prepares body for stressful or dangerous situations

leptin (hormone)

regulates appetite and energy balance; plays role in cognitive functions like learning and memory

ghrelin (hormone)

appetite increaser; released in the stomach and stimulates the hypothalamus to increase appetite

melatonin (hormone)

helps regulate body’s circadian rhythms or 24 hour internal clock; produced in response to darkness

oxytocin (hormone)

plays a role in social bonding, trust, and relationship building; “love hormone” “cuddle chemical”

agonist

a molecule that increases a neurotransmitter’s action.

antagonist

a molecule that inhibits or blocks a neurotransmitter’s action.

reuptake inhibitors

a drug that prevents nerve cells from reabsorbing neurotransmitters, which increases neurotransmitter levels in brain. can lead to mood alternation

cell body

the part of a neuron that contains the nucleus; the cell’s life-support center.

dendrites

a neuron’s often bushy, branching extensions that receive and integrate messages, conducting impulses toward the cell body.

axon

the segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands.

myelin [MY-uh-lin] sheath

a fatty tissue layer segmentally encasing the axons of some neurons; it enables vastly greater transmission speed as neural impulses hop from one node to the next.

synapse [SIN-aps]

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.

neurotransmitters

chemical messengers that cross the synaptic gap between neurons. affect movement senses and mood; each has its own unique structure that fits into a specific receptor

endocrine [EN-duh-krin]

system the body’s “slow” chemical communication system; a set of glands and fat tissue that secrete hormones into the bloodstream.

hormones

chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues.

substance use disorder

a disorder characterized by continued substance use despite resulting life disruption.

psychoactive drug

a chemical substance that alters the brain, causing changes in perceptions and moods.

depressants (alcohol)

drugs that reduce neural activity and slow body functions.

stimulants

drugs that excite neural activity and speed up body functions.

opioids (heroin)

opium and its derivatives; they depress neural activity, temporarily lessening pain and anxiety.

hallucinogens (marijuana)

psychedelic (“mind-manifesting”) drugs that distort perceptions and evoke sensory images in the absence of sensory input.

addiction

an everyday term for compulsive substance use (and sometimes for dysfunctional behavior patterns, such as out-of-control gambling) that continue despite harmful consequences. (See also substance use disorder.)

withdrawal

the discomfort and distress that follow discontinuing an addictive drug or behavior.

tolerance

the diminishing effect with regular use of the same dose of a drug, requiring the user to take larger and larger doses before experiencing the drug’s effect.

barbiturates

drugs that depress central nervous system activity, reducing anxiety but impairing memory and judgment.

near-death experience

an altered state of consciousness reported after a close brush with death (such as cardiac arrest); often similar to drug-induced hallucinations.

biological psychology

the scientific study of the links between biological (genetic, neural, hormonal) and psychological processes. Some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists.

biopsychosocial approach

an integrated approach that incorporates biological, psychological, and social-cultural levels of analysis.

levels of analysis

the differing complementary views, from biological to psychological to social-cultural, for analyzing any given phenomenon.

neuroplasticity

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

lesion [LEE-zhuhn]

tissue destruction. Brain lesions may occur naturally (from disease or trauma), during surgery, or experimentally (using electrodes to destroy brain cells).

lesioning procedures

a group of techniques that destroy targeted brain tissue or nerves to treat a variety of conditions

EEG (electroencephalogram)

an amplified recording of the waves of electrical activity sweeping across the brain’s surface. These waves are measured by electrodes placed on the scalp.

MEG (magnetoencephalography)

a brain-imaging technique that measures magnetic fields from the brain’s natural electrical activity.

CT (computed tomography) scan

a series of X-ray photographs taken from different angles and combined by computer into a holistic representation of a slice of the brain’s structure.

PET (positron emission tomography)

a technique for detecting brain activity that displays where a radioactive form of glucose goes while the brain performs a given task.

MRI (magnetic resonance imaging)

a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. ___ scans show brain anatomy.

fMRI (functional MRI)

a technique for revealing blood flow and, therefore, brain activity by comparing successive ___ scans. ____ scans show brain function as well as structure.

hindbrain

consists of the medulla, pons, and cerebellum; directs essential survival functions, such as breathing, sleeping, and wakefulness, as well as coordination and balance.

midbrain

found atop the brainstem; connects the hindbrain with the forebrain, controls some motor movement, and transmits auditory and visual information.

forebrain

consists of the cerebral cortex, thalamus, and hypothalamus; manages complex cognitive activities, sensory and associative functions, and voluntary motor activities.

brainstem

the central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions.

medulla [muh-DUL-uh]

the hindbrain structure that is the brainstem’s base; controls heartbeat and breathing.

thalamus [THAL-uh-muss]

the forebrain’s sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla.

reticular activating system (RAS)

a network of neurons in the brainstem that regulates sleep wake cycles, arousal and attention

reward center

a collection of brain structures and neural pathways that are responsible for reward-related cognition (motivation and “wanting” desire, craving for reward)

cerebellum [sehr-uh- BELL-um]

the hindbrain’s “little brain” at the rear of the brainstem; its functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory.

limbic system

neural system located mostly in the forebrain — below the cerebral hemispheres — that includes the amygdala, hypothalamus, hippocampus, thalamus, and pituitary gland; associated with emotions and drives.

amygdala [uh-MIG-duh-la]

two lima-bean–sized neural clusters in the limbic system; linked to emotion.

pituitary gland

master gland; control release of growth hormone and others

thalamus

receives sensory information from sensory neurons (except for smell); sends sensory info to appropriate areas of brain for processing

hypothalamus [hi-po-THAL- uh-muss]

a limbic system neural structure lying below (hypo) the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system, and is linked to emotion and reward.

hippocampus

a neural center in the limbic system that helps process explicit (conscious) memories — of facts and events — for storage.

cerebral [seh-REE-bruhl] cortex

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

frontal lobes

the portion of the cerebral cortex lying just behind the forehead. They enable linguistic processing, muscle movements, higher- order thinking, and executive functioning (such as making plans and judgments).