Unit 1 AP Psychology 2024

Biological Bases of Behavior

heredity / nature (i.e., genetic predisposition)

the genetic transfer of characteristics from parents to offspring

environment / nurture

every nongenetic influence (e.g., prenatal nutrition, education, etc.)

chromosome

structure in the nucleus of cells that contains genes determined by DNA sequences (46 chromosomes in total)

DNA

a complex molecule containing the genetic information that makes up the chromosomes

gene

each DNA segment of a chromosome that determines a trait (~20,000 genes)

genotype

the genetic makeup (i.e., genes) for a trait of an individual

phenotype

the observable expression of genes (e.g., seeing that someone has blue eyes and brown hair)

identical (monozygotic) twins

two individuals who share all of the same genes/heredity because they develop from the same fertilized egg (zygote)

fraternal (dizygotic) twins

share about half of the same genes because they develop from two different fertilized eggs or zygotes

family studies

a form of research that can indicate the impact of genes and/or shared environments on a wide number of different behaviors / characteristics, including intelligence, sexual orientation, temperament, mental disorders, etc.

twin studies

a form of research involving twins that can indicate the impact of genes and/or shared environments on a wide number of different behaviors / characteristics, including intelligence, sexual orientation, temperament, mental disorders, etc.

heritability

the amount of variation among individuals in a group that we can attribute to genes

interaction

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

behavior genetics

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

evolutionary psychology

the study of how natural selection favors behaviors that contributed to the survival and spread of our ancestors' genes (i.e., genetic inheritance) and may currently explain human behavior

natural selection

the idea that inherited traits that enable an organism to survive/reproduce in an environment (compared with other traits) will most likely be passed on to successive generations

mutation

random error in gene replication

social script

a culturally modeled guide for how to act in various situations

central nervous system (CNS)

consists of the brain and spinal cord; the brain is the body's "decision-maker"; the spine is the super highway of nerves (transmitting info to and from brain)

interneurons

neurons in the brain and spinal cord that communicate "internally" and process information between the sensory inputs and motor outputs (i.e., they intervene between the sensory and motor neurons)

peripheral nervous system (PNS)

outside the midline portion of the nervous system; carries sensory information to the CNS (sensory [afferent] neurons); carries motor information away from the CNS (motor [efferent] neurons)

nerves

bundled axons that connect CNS with muscles, glands and sense organs

sympathetic nervous system processes

fight or flight" mechanism; (effect of epinephrine, aka adrenaline): elevated heart rate, slowed digestion, high blood sugar, more perspiration, dilated pupils (pupils enlarge)

parasympathetic nervous system processes

"rest and digest" mechanism; (body restores homeostasis): increased digestion, blood sugar, perspiration, heart rate return to normal, pupils constrict

sensory (afferent) neurons

carries sensory information to the CNS

motor (efferent) neurons

carries motor information away from the CNS to effectors (i.e., muscle and gland cells)

the endocrine system

glands in the body that secrete chemical messengers into the blood

hormones

chemical messengers that travel to particular organs (through the bloodstream) and bind to specific receptors (and alter organ function on a cellular level); hormones that effect the brain can alter interest in sex, food and aggressive behavior

melatonin

this hormone regulates circadian rhythms (also associated with seasonal affective disorder)

oxytocin

hormone that enhances emotional bonding

cortisol

"the stress hormone"; a stress hormone that stimulates the body to produce fat; cortisol levels can increase due to stressful experiences and/or a lack of sleep

epinephrine (aka adrenaline)

hormone that brings about "fight or flight" response; arouses the body during times of stress

insulin

hormone that regulates blood sugar levels (i.e., makes sure that blood sugar levels do not become too high)

estrogen

hormone that aids in development of female secondary sexual characteristics

testosterone

hormone that aids in development of male secondary sexual characteristics; associated with aggressive behavior

glucose

a sugar commonly found in the bloodstream; essential source of energy for organs

ghrelin

hormone secreted by empty stomach; sends "I'm hungry" signals to the brain (i.e., increases levels of perceived hunger)

orexin

hunger-prompting hormone secreted by hypothalamus

insulin

hormone secreted by pancreas; controls blood glucose and decreases appetite

leptin

protein hormone produced by fat cells; high levels of leptin causes brain to increase metabolism and decrease hunger

PYY

digestive tract hormone; sends "I'm not hungry" signals to the brain

axon

longest part of neuron; electrical message travels through

dendrites

part of the neuron that receives incoming transmitters (i.e., messages)

soma

cell body of the neuron; contains the nucleus

myelin sheath

fatty tissue that insulates axon of the neuron; speeds up message transmission

axon terminal buds

end point of neuron; release neurotransmitters into the synapse (tiny junction with next neuron)

schwann cells

cells that create (i.e., make up) the sections of the myelin sheath

nodes of ranvier

space between schwann cells; high density of ion channels present in the nodes of ranvier

glial cells

cells that provide structure, insulation, communication and waste transport; Ex: schwann cells and oligodendrocytes

multiple sclerosis

a disorder where symptoms include double vision, vision loss, eye pain, muscle weakness, and a loss of sensation or coordination (results from deterioration of myelin sheaths protecting nerve cells)

neurotransmitters

chemical substance that is released into the synaptic gap and signals to the next neuron to continue the action potential

synaptic gap/cleft (or simply synapse)

open space between two neurons at which neurotransmitters cross (N.B.: just a gap à does not actively control the firing process)

receptor sites (on the post-synaptic membrane)

specific places on dendrites that receive specific types of neurotransmitters

reuptake

a neurotransmitter's reabsorption by the sending neuron

action potential

slight change in voltage developed across the cell membrane due to the exchange of ions in and out of the neuron

resting potential

when a neuron is NOT firing, and has a negative charge in the axon

homeostasis

a resting state (negative charge within the axon, positive charge outside of the axon); neurons constantly strive to achieve this state

depolarization

when "opposites" are no longer set apart from one another; when this happens in the earlier part of the axon, it creates a domino effect; sodium ions flow in (inside of the neuron develops a positive charge)

repolarization

potassium ions flow out to recreate negative resting potential charge

hyperpolarization

the stage that occurs when the membrane potential becomes more negative than its usual resting state (this negativity is due to an outward movement of positive potassium ions out of the cell)

refractory period

the period of time after firing that the neuron starts resetting (the sodium and potassium ions return to their original state); subsequent action potentials cannot occur until the axon returns to its resting state

all-or-nothing principle

the neuron either fires or does not fire; there is no "half-firing" or "minimal level of firing"; it fires all the way down the axon

excitatory signals

the neurotransmitters cause the neuron on the other side of the synapse to generate an action potential (i.e., to fire) through depolarization (e.g., ACh stimulates muscle contraction through depolarization of the receiving neuron)

inhibitory signals

the neurotransmitters cause the neuron on the other side of the synapse to experience hyperpolarization (opposite of depolarization; means that even more/larger ( stimulus will be needed to cause the neuron to fire) (this leads the neurons farther away from depolarization (i.e., it will be even harder for them to fire) (e.g., GABA inhibits involuntary muscle movement)

acetylcholine (ACh)

neurotransmitter that allows muscle contractions, memory and learning; with Alzheimer's disease, ACh-producing neurons deteriorate

dopamine

neurotransmitter that affects alertness, attention, emotion; can generate rewarding sensation; lack of dopamine results in Parkinson's Disease; too much dopamine results in schizophrenia

serotonin

neurotransmitter that is associated with sexual activity, concentration and attention; also with moods and emotions; lack of serotonin depression

norepinephrine

physical arousal, learning and memory; Lack of norepinephrine results in depression, stress

GABA (gamma-aminobutyric acid)

inhibitory neurotransmitter; inhibits firing of neurons (i.e., inhibition of brain activity); can cause anxiety disorders (due to Insufficient GABA-producing neurons); malfunctioning GABA systems results in seizures

glutamate

excitatory neurotransmitter; involved in memory formation in hippocampus; too much glutamate results in migraines, seizures

endorphins

endogenous [produced within} morphine; released through intense physical exercise; Influence pain/pleasure perception, "runners high; Lack of endorphins (caused by opiate abuse) results in opiate addiction

substance p

excitatory neurotransmitter; involved in pain transmission and immune system response (i.e., tissue inflammation); when released, can stimulate nausea and vomiting; increased levels of substance p may contribute to depressed mood and chronic pain (antagonists for this neurotransmitter have been effective in treating depression)

opiates

powerful painkillers; when overused, can adversely (i.e., negatively) affect the body's ability to produce natural painkillers (i.e., endorphins) and result in uncomfortable withdrawal symptoms

agonist molecules

chemicals (typically drugs) that increase neurotransmitter's action; mimic neurotransmitter activity (work like a master key)

antagonist molecules

chemicals (typically drugs) that decrease a neurotransmitter's action by blocking receptor site on receiving neuron; block neurotransmitter activity (work like a fake key, failing to open the door but also blocking other neurotransmitters)

psychoactive drug

a chemical that can pass through the blood-brain barrier to alter perception, thinking, behavior and mood

substance use disorder

condition where subject continually craves the use of a substance despite risks to health and disruption to lifestyle

blood-brain barrier

a border of blood vessels in the brain that do not allow blood of the peripheral nervous system to impact the central nervous system (psychoactive drugs can cross over this barrier)

tolerance

diminished psychoactive effects after repeated use; contributes to addiction because drug users take increasing amounts of the drug to get the desired effects.

withdrawal (after addiction)

(after addiction), when user stops taking the drug, may experience mild to severe physical discomfort, intense cravings (i.e., physical dependence) and/or negative emotions (psychological dependence)

depressants

drugs that reduce neural activity and slow body functions; includes alcohol, barbiturates (tranquilizers), opiates

alcohol consumption

suppresses sympathetic nervous system activity (i.e., relaxes drinker, lowers inhibitions and judgments); interferes with REM sleep; over long periods, kills nerve cells and inhibits the growth of new nerve cells

barbiturate consumption

depresses nervous system activity (mimics the effects of alcohol); includes nembutal, seconal, amytal, etc.; used to induce sleep or reduce anxiety; overuse might result in memory or judgment impair; potentially lethal if combined with alcohol

opiate consumption

when the brain is flooded with artificial opiates again and again, it stops producing endorphins (thus highly addictive); when the effect of the opiates wears off, the body is left devoid of endorphins and the user feels extreme discomfort (i.e., withdrawal symptoms); includes heroin and pain-relief narcotics codeine, morphine, and methadone

stimulants

psychoactive drugs that activate motivational centers and reduce activity in the inhibitory centers of the central nervous system by increasing neurotransmitters; includes caffeine, nicotine, cocaine, amphetamines, methamphetamine (aka "meth" or "speed") and ecstasy

consuming caffeine

mimics adenosine (a neurotransmitter); increases attentiveness & improves mood; physically addictive; withdrawal symptoms include headaches, irritability, drowsiness

using nicotine

signals to central nervous system to release epinephrine and norepinephrine, which lessens appetite and boosts alertness and mental efficiency; signals to central nervous system to release dopamine and opioids, which momentarily alleviates anxiety and reduces sensitivity to pain; withdrawal symptoms include irritability, intense cravings, potential weight gain

cocaine consumption

blocks sites on sending neuron, preventing neurotransmitter molecules (dopamine, norepinephrine, and serotonin) from being reabsorbed (i.e., preventing reuptake); neurotransmitters remain in the synapse, producing a feeling of euphoria; when cocaine levels drop, there are not enough neurotransmitters left, so the user experiences an overwhelming feeling of depression

amphetamine consumption

triggers the release of neurotransmitters (e.g., dopamine), which stimulates brain activity, enhances energy and improves mood; side-effects include irritability, insomnia, hypertension, seizures, social isolation, depression and potential violent outbursts (Homer et al., 2008)

ecstasy consumption

triggers dopamine release (similar to amphetamine), which releases stored serotonin and blocks reuptake (you should know this word by now); creates a pleasurable sensation; combined with intense physical activity, can lead to over-heating, increased blood pressure and death; continual use may result in damage to serotonin-producing neurons, which will result in a permanently depressed mood

hallucinogens (psychedelics)

drugs that alter moods, distort perceptions, and evoke sensory images in the absence of sensory input

LSD consumption

drug that causes the visual cortex becomes hypersensitive and strongly connected to the brain's emotional centers; people may experience a feeling of being separated from their own bodies (similar to near-death experiences)

THC (marijuana) consumption

triggers mild hallucinations and possibly euphoria; relaxes the user; may be used to alleviate chronic pain and nausea in cancer patients receiving chemotherapy; can possibly amplify feelings of anxiety and depression in people who struggle with those issues, particularly after the effects have worn off; may also result in impaired attention, learning and memory

lesion

destruction of tissue (in our case, brain tissue); can be caused naturally or experimentally

stimulation

to manipulate various parts of the brain using chemicals, electrical current or magnetic forces

optogenetics

using light to control the activity of individual neurons

electroencephalogram (EEG)

electrodes placed at specific positions on the scalp are used to trace the brain's surface electrical activity (i.e., "brain waves") with the help of a machine; records changes in voltage (i.e., electrical current) resulting from a person's response to a stimulus

evoked potentials

recorded changes in voltage (i.e., electrical current) resulting from a person's response to a stimulus

functional MRI (fMRI)

changes in the oxygen level of blood create changes in the magnetic qualities of different brain areas these changes in magnetic qualities are detected by the fMRI machine; can simultaneously highlight brain structure and brain function (i.e., which areas of the brain activate during different activities)

medulla

"swelling" in the spinal cord before entering skull; controls heartbeat and breathing