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Biological Psychology > Chapter 4 > Flashcards

Chapter 4 Flashcards

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1
Q

neurotransmitter

A

chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons
- qualifications:
+ substance exists in presynaptic axon terminals
+ is synthesized in presynaptic cells
+ is released when action potentials reach axon terminals
+ receptors for the substance exist on postsynaptic membrane
+ when applied, substance produces changes in postsynaptic cells
+ blocking substance release prevents changes in postsynaptic cell

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2
Q

types of receptors

A
  • ionotropic: fast; open an ion channel when the transmitter molecule binds; fast onset + decay (millisecond)
  • metabotropic: slow; alter chemical reactions in the cell (e.g. G protein system) to open an ion channel; slower onset, long response and duration (second or minute)
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3
Q

ligand

A

substance that fit receptors exactly and activates or blocks them
- categories:
+ endogenous: produced inside the body (e.g. neurotransmitters and hormones)
+ exogenous: produced outside of body (e.g. drugs and toxins)

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4
Q

types of ligands

A
  • agonist: initiates or activates the normal effects of the receptor
  • antagonist: blocks the receptor from being activated by other ligands
  • inverse agonist: initiates an effect that is the opposite of the normal function
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5
Q

drugs as exogenous ligands

A
  • if act as agonists, antagonists or inverse agonists: COMPETITIVE ligands - bind to the same part of receptor molecule as endogenous ligands
  • NONCOMPETITIVE ligands (also called neuromodulators): bind to modulatory sites that are not part of the receptor complex that normally binds the transmitter
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6
Q

types of neurotransmitters

A
  • amine: acetylcholine, dopamine, norepinephrine, adrenaline, serotonin
  • amino acid: GABA, glutamate
  • peptide
  • gas: nitric oxide, carbon dioxide
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7
Q

acetylcholine (ACh)

A

mapped by enzymes involved in synthesis; stored in cholinergic nerve cell bodies and projections
+ roles: signaling muscle movement, sensation of pain, learning + memory formation, regulation of endocrine system, sleep

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8
Q

dopamine (DA)

A
  1. found in substantia nigra of the mesostriatial pathway (in midbrain)
    - role: motor control (neuronal loss in pathway leads to Parkinson’s disease)
  2. found in ventral tegmental area (VTA) of the mesolimbocortical DA pathway (in midbrain)
    - role: reward, reinforcement, and learning (abnormalities lead to schizophrenia & neurodegenerative diseases)
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9
Q

norepinephrine (NE)

also called noradrenaline

A

released in 3 brainstem regions: locus coeruleus (pons), lateral tegmental system (midbrain), and dorsal medullary group
- role: modulate processes of mood, arousal, and sexual behavior

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10
Q

serotonin (5-HT)

A

found in raphe nuclei

- role: sleep, mood, sexual behavior, anxiety

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11
Q

amino acid transmitters

A
  • GABA: inhibitory - trigger IPSP
  • glutamate: excitatory - trigger EPSP
    + excitotoxicity: neural injury such as stroke may cause excess release of glutamate, which is toxic to neurons
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12
Q

peptide

A

2+ amino acids linked in a chain; act as neurotransmitters or hormones

  • opioid peptides: mimic opiate drugs (e.g. morphine)
  • peptides in gut, spinal cord, or brain
  • pituitary hormones
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13
Q

nitric oxide (NO)

A

produced in dendrites, diffuses as soon as it is produced into target cell and stimulates production of second messengers

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14
Q

mechanism of drugs

A

affect synaptic transmissions: either act on presynaptic terminals or postsynaptic membrane
- e.g. local anesthetics block sodium channels and therefore block action potentials in pain fibers

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15
Q

agonist vs. antagonist drugs

A
  • agonist: initiates or activates normal effects of receptor
    + e.g. dopamine, morphine, nicotine
  • antagonist: blocks receptor from being activated by other ligands
    + e.g. haloperidol (treatment of schizophrenia)
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16
Q

affinity

or binding affinity

A

degree of chemical attraction between a ligand and receptor

  • high level: drug will bind with matching receptor even at low doses and stay for a relatively long time
  • low level: drugs bind fewer receptor molecules
17
Q

efficacy

or intrinsic activity

A

ability of a bound ligand to activate the receptor

- agonists -> high efficacy, antagonists -> low

18
Q

dose-response curve (DRC)

A

graph of the relationship between drug doses and the effects (effects - y axis, dose - x axis)

  • effective dose 50% (ED50): dose at which the drug shows half of its maximal effect
  • comparable effects at lower doses -> more potent
19
Q

tolerance

A

condition in which an individual becomes less responsive to a drug after repeated exposure (continued use)

  • mechanism: body = regulatory feedback system to protect against unbalanced brain chemistry -> adapts to presence of drugs to offset effects -> develops tolerance
  • as tolerance develops, more of the drug is needed to produce the same effect
20
Q

types of tolerance

A
  • metabolic: organ systems become more effective at eliminatingw/cleaning the drug (e.g. liver) before it has a chance to affect the brain
  • functional: target tissue may decrease sensitivity to drug as a result of change in # of receptors present in cell membrane
    + down regulate: decrease # of receptors - response to agonists
    + up regulate: increase # of receptors - response to antagonists
21
Q

withdrawal symptoms

A

unpleasant sensations that occur when one stops using a drug

  • can be psychological (e.g. anxiety, irritability, depression, etc.) or physical (e.g. tremors, nausea, sweating, etc.)
  • prolonged + repeated use of drugs change the way nerve receptors work in the brain and make them dependent upon the drug to function
  • recreational drugs trigger dopamine release in reward system -> addictive
22
Q

drug effects on presynaptic mechanisms

A
  • affect transmitter synthesis enzymes
  • affect storage in vesicles
  • postsynaptic receptors can be blocked or activated by drugs
23
Q

drugs as presynaptic control

A

affect transmitter reuptake (how long transmitters remain in synapse) and interfere with transporters (specialized proteins that return transmitter to the presynaptic membrane)

  • cocaine: alleviates hunger, promotes endurance, enhances sense of well-being; blocks monoamine transporters (especially dopamine) and slows reuptake
  • caffeine: blocks adenosine and stimulates catecholamine (e.g. dopamine) release -> causes arousal
24
Q

drugs as postsynaptic control

A
  • nicotine: increases heart rate, blood pressure, hydrochloric acid secretion, and bowel activity; acts as agonists on nicotinic ACh receptors in body & brain
  • alcohol: biphasic effects - stimulant phase followed by depressant phase; activate GABA receptors and increases inhibitory effects; stimulates dopamine pathways; induces social disinhibition, loss of motor coordination, and feeling of euphoria
    + chronic use seriously affects frontal lobes & shrinks cortex + kills neurons
    + periodic overconsumption (bingeing) may cause brain damage and reduce neurogenesis
  • marijuana: causes relaxation, mood alteration, stimulation, hallucination, and paranoia
25
Q

drug abuse

A

reason: drugs cause strong feeling of euphoria or reward via dopamine release in nucleus accumbens
- drugs stimulate reward pathway in VTA

26
Q

models of drug abuse

A
  • physical dependence model:
    + also called withdrawal avoidance model
    + theory: abusers use drugs to avoid withdrawal symptoms (negative reinforcement)
    + BUT some addicted patients do not experience strong withdrawal symptoms
  • positive reward model:
    + theory: drug use is a behavior controlled by positive rewards
    + pleasant sensations and behaviors associated with addictive drugs increase probability of use
    + addictive drugs are positive reinforcers that increase the effect of dopamine receptor in the limbic system

Biological Psychology (9 decks)

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