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Flashcards in Chapter 6 Deck (91):
1

Psychoactive Drugs

substances that act to alter mood, thought or behavior, are used to manage neuropsychological illness and may be abused

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Route of Administration

way in which a drug enters and passes through the body to reach its target

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Oral Administration

Easy and convenient; most complex route. Must be absorbed through the stomach lining or small intestine to enter the blood stream

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In order to pass into the blood stream a drug must be....

soluble in water because blood has a high concentration of water

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Gas or Aerosol Administration

penetrate the cell linings of the respiratory tract; are easily absorbed across these membranes into the bloodstream

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Skin Administration

small molecule drugs penetrate the skin's barrier (nicotine)

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When obstacles are eliminated en route to the brain

the dosage of a drug can be reduced by a factor of 10

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Blood-brain barrier

tight junctions between the cells of blood vessels in the brain that prevent the passage of most substances; protects the brain from many circulating hormones, toxic and infectious substances

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Brain Capillaries--> Tight Junctions

Capillaries are formed by a single layer of endothelial cells; not fused in most parts of the body but ARE fused in the brain--> causing tight junctions

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Where does the blood-brain barrier not exist?

postrema of the lower brainstem allows toxic substances in the blood to trigger a vomiting response; Pineal gland enables hormones to reach it to modulate day-night cycle; Pituitary is triggered in part by other hormones

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What does the brain need to work?

oxygen, glucose, amino acids

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How do essential molecules cross the BBB?

small molecules (oxygen and carbon dioxide) pass through the endothelial membrane; glucose, amino acids and other food components are carried across by active-transport systems (Ion-pumps-transporter proteins)

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Catabolize

breaking down and removal of drugs by the body

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What part of the body is especially important in catabolizing drugs?

Liver.

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Drug neurotransmission at a synapse

1. Synthesis of the neurotransmitter can take place in the cell body, axon or terminal 2. Storage of the neurotransmitter in granules, vesicles or both 3. Release of the transmitter from the terminal's presynaptic membrane into the synapse 4. Receptor Interaction in the post synaptic membrane, transmitter acts on an embedded receptor 5. Inactivation of excess neutransmitter at the synapse 6. Reuptake into the presynaptic terminal for reuse 7. Degradation of excess neurotransmitter by synaptic mechanisms and removal of unneeded by-products from the synapse

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Agonists

Drugs that increase neurotransmission

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Antagonists

Drugs that decrease neurotransmission

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Acetylcholine

agonists that excite muscles

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Acetycholine Antagonists

Botulin Toxin (blocks release) Curare (blocks receptors)

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Acetycholine Agonists

Choline-rich diets Black widow spider venom (promotes release) Nicotine (stimulates receptors) Physostigmmine (blocks inactivation) Organophosphates (blocks inactivation)

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Tolerance

decrease in response to a drug with the passage of time

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Three kinds of tolerance

metabolic, cellular, learned

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Metabolic toelrance

number of enzymes needed to break down alcohol in the liver, blood and brain increases. As a result, any alcohol that is consumed is metabolized more quickly, so blood-alcohol levels are reduced

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Cellular Tolerance

activities of brain cells adjust to minimize the effects of alcohol present in the blood

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Learned Tolerance

can help explain a drop in the outward signs of intoxication. Learn how to cope with influences of alcohol

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When are people most likely to experience drug sensitization?

when they are occasional users.

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Drug sensitization

increased responsiveness to successive equal doses; may manifest as a progressive increase OR decrease in emitted behavior

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Neural basis of sensitization

occurs a number of ways: increase of neurotransmitter at presynaptic terminal, changes in # of receptors on the postsynaptic membrane, changes in the rate of transmitter metabolism in the synaptic space, changes in transmitter reuptake by the presynaptic membrances, changes in the size and # of synapses

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Sensitization and environment

showing a change in learned responses to cues in the environment as sensitization progresses. Before someone becomes addicted they must have a number of experiences with the drug away from the home environment

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Classes of Drugs

I Antianxiety agents and sedative hypnotics II antipsychotic agents III antidepressant and mood stabilizers IV opioid analgesics V psychotropics

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Antianxiety Agents

drugs that reduce anxiety; minor tranquilizers (benzodiazepines) are to aid in sleep; sedative hypnotic agents (barbiturates and alcohol) are sedatives and sleep agents

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Characteristic of sedative hypnotics

user develops a tolerance

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Cross-Tolerance

tolerance developed for one drug is carried over to a different member of the drug group

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Target for sedative hypnotic and antianxiety drugs

GABA (GABAa contains a chloride ion channel), Inhibitory effect of GABA--reduce neuronal firing. Also responds to PCP, GHB and special K

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Antipsychotic Agents

first-generation= phenothiazines (chlorpromazine, thorazine) and butyrophenones (haloperidol, haldol)--> work by blocking D2 receptor (reduces motor activity and alleviates excessive agitation)

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Dopamine Hypothesis of Schizophrenia

idea that excess activity of the neurotransmitter dopamine causes symptoms of schizophrenia

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LSD

produces symptoms similiar to schizophrenia; serotonin agonist that acts on the 5-HT2 receptor

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PCP and Special K

produce schizophrenia-like symptoms; formerly used as anesthetics; block glutamate receptors

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Antidepressants and Mood stabilizers

Used for Major Depression and bipolar disorder

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Antidepressant medications

include: Monoamine oxidase (MAO) inhibitors, tricyclic antidepressants, and second-generation antidepressants. Improve chemical neurotransmission at serotonin, noradrenaline, histamine, acetylcholine, and dopamine synapses. All are AGONISTS

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MAO Inhibitor

provides for more serotonin release with each action potential by inhibiting monoamine oxidase (enzyme that breaks down serotonin within the axon terminal)

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Tricyclices and Second generation antidepressants

block the reuptake transporter that takes serotonin back into the axon terminal

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Selective Serotonin Reuptake Inhibitors

tricyclic antidepressant drug that blocks the reuptake of serotonin into the presynaptic terminal

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Second Generation Antidepressant

drug whose action is similar to that of tricyclics but more selective in its action on the serotonin reuptake transporter proteins

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Antidepressants take how long to work?

weeks. May be because they stimulate second messengers in neurons to activate repair of those damaged by stress

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Mood stabilizers

(lithium) mute the intensity of one pole of bipolar disorder, thus making the other less likely to occur. Does not directly affect mood--> may stimulate neuronal repair.

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Opioid Analgesics

Drug like morphine, with sleep-inducing (narcotic) and pain-relieving (analgesic) properties

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Sources of Opioids

Opium can be synthesized into: codeine (pain reliever that is transformed into morphine by the liver) and morphine (pain reliever) Brain- peptides in the body have opioid-like effects (endorphines)

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Endorphin

peptide hormone that acts as a neurotransmitter and may be associated with feelings of pain or pleasure; mimicked by opioid drugs such as morphine, heroine, opium and codeine

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Classes of endorphins

Endomorphins enkephalins dynorphins

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Endorphin receptors

mu kappa delta

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Morphine

most closely mimics endomorphins and binds most selectively at mu

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Heroin

affects mu receptors; is synthesized from morphine; more fat-soluble and penetrates the BBB more quickly

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Competitive inhibitor

drugs such as nalorphine and naloxone that acts quickly to block the actions of opioids by competing with them for binding sites; used to treat opioid addictions

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Effects of opioids

pain relief, relaxation, sleep, euphoria, constipation, respiratory depression, decreased blood pressure, pupil constriction, hypothermia, drying of secretions, reduced sex drive, flushed warm skin

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Psychotropics

stimulants that mainly affect mental activity, motor activity, arousal, perception and mood

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Behavioral stimulants

affect motor activity and mood

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Psychedelic and Hallucinogenic Stimulants

affect perception and produce hallucinations

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General Stimulants

Affect mood

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Amphetamine

behavioral stimulant; synthetic compound (attempts to synthesize epinephrine); dopamine agonist that acts frist by blocking the dopamine reuptake transporter; also stimulates DA from presynaptic membranes

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Cocaine

Behavioral stimulant; dopamine agonist that acts frist by blocking the dopamine reuptake transporter; extracted from Peruvian coca shrub

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Methamphetamine

amphetamine derivative

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Psychedelic and Hallucinogenic Stimulants

alter sensory perception and cognitive processes and can produce hallucinations

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Types of psychedelicss

Acetylcholine, anandamide, glutamate, norepinephrine, serotonin

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Acetylcholine Psychedelics

either both (atropine) or facilitate (nicotine) transmission at acetylcholine synapses

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Anandamide Psychedelics

endogenous neurotransmitter that enhances forgetting; prevents brain's memory systems from being overwhelmed; THC acts on receptors for anandamide (CB1 and CB2)

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Glutamate Psychedelics

PCP and Ketamine --block glutamate NMDA receptors (receptors involved in learning)

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Norepinephrine Psychedelics

Mescaline (peyote cactus) produces a sense of spatial boundlessness and visual hallucinations

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Serotonin Psychedelics

LSD and psilocybin (obtained from shrooms) stimulate serotonin receptors and block the activity of other serotonergic neurons through serotonin autoreceptors. May stimulate other transmitter systems (such as norepinenrine --> ecstasy)

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General Stimulants

drugs that cause an overall increase in the metabolic activity of the cells. Ex. Caffeine

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Disinhibition Theory

explanation holding that alcohol has a selective depressant effect on the cortex, the region of the brain that controls judgment, while sparing subcortical structures responsible for more primitive instincts, such as desire

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Alcohol Myopia

"nearsighted" behavior displayed under the influence of alcohol: local and immediate cues become prominent, and remote cues and consequences are ignored

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Substance Abuse

Use of a drug for the psychological and behavioral changes it produces aside from its therapeutic effects

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Addiction

Desire for a drug manifested by frequent use of the drug, leading to the development of physical dependence in addition to abuse; often associated with tolerance and unpleasant, sometimes dangerous, withdrawal symptoms on cessation of drug use

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Withdrawal Symptom

physical and psychological behavior displayed by an addict when drug use ends; includes muscle aches, cramps, anxiety, sweating, nausea, convulsions, death

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Psychomotor Activation

increased behavioral and cognitive activity; at certain levels of consumption, the drug user feels energetic and in control

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Abused Drugs

may act on the same target in the brain: dopamine in the mesolimbic pathways of the dopaminergic activating system; abused drugs increase DA directly or indirectly

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Sex and Addiction

females are twice as sensitive to drugs as males; females are more likely to abuse nicotine, alcohol, cocaine, amphetamine, opioids, cannabinoids, caffeine, and PCP

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Wanting-and-Liking-Theory

AKA incentive-sensitization theory; Wanting = cravings, Liking= pleasure from drug taking; with repeated use, tolerance for liking develops and pleasure decreased BUT wanting sensitizes

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Where the decision to take a drug takes place

Frontal cortex

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Where liking takes place

opioid systems in the brainstem--> pleasurable experiences

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Where wanting takes place

activity in the mesolimbic pathways of the dopaminergic activating system

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Learning and Drug Use

repeated pairings of drug-related cues to drug taking forms neural associations in the dorsal striatum (basal ganglia); cues associated with drug taking influence decisions to take or continue to take drugs

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Epigenetics and Addiction

addictive drugs can influence gene regulation by determining which genes are expressed

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Brain Damage and Glutamate

MSG and glutamate--results in influx of Ca2+ into the cell-->second messenger-->suicide gene--> cell death

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Apoptosis

cell death

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Brain damage and Alcohol

thalamus and limbic system damage, may be due to a lack of thiamine (B1)

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MDMA and Brain Damage

degeneration of fine serotonergic nerve terminals

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Cocaine and Brain Damage

blocks cerebral blood blow; brain regions reduce in size

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THC and Brain Damage

may cause psychosis, but has neuroprotective properties; aids in healing after TBI and slows progression of Alzheimer's and Huntington's

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Testosterone

sex hormone secretes by the testes and responsible for distinguishing characteristics of the male