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Lecture 4

BPK 140 Lecture Notes - Lecture 4: Nucleus Accumbens, Drug Intolerance, Hypodermic Needle

Biomedical Physio & Kines
Course Code
BPK 140
Gibson Steve

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Week 4: Licit and Illicit Drug Use: Understanding Addictions
Study Questions:
- drug use: taking a drug for the reason it was intended (e.g. for what it was prescribed for)
- drug misuse: the use of a drug for a purpose for which it was not intended
- drug abuse: the excessive use of any drug
1. Describe how set and setting influence the side effects of psychoactive drugs.
- set: the total internal environment or mindset of a person at a time a drug is taken (e.g.
expectations on the effects of the drugs, mood); will affect the experienced side effects
- setting: the drug user’s total external environment; e.g. drug will produce different affect at a
club setting than in at home
2. Outline the list of behaviours generally exhibited by a person with an addiction.
- at least 3 of the following:
- makes excessive use of a substance or behaviour (longer than period of time intended)
- expresses a persistent desire or makes unsuccessful efforts to control use of substance or
- spends great deal of time getting or using substance or engaging in behaviour or recovering
from its effects and after-effects
- frequently too incapacitated by after-effects to fulfill major obligations
- gives up regular activates to use substance or engage in the behaviour
- continues to use substance or participate in the activity despite problems with it
- develops a physical tolerance (needs more to get the same effect)
- exhibits withdrawal when not using the substance or engaging in the behaviour
- uses or engages in behaviour to relieve or avoid withdrawal symptoms

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3. Differentiate between physiological and psychological dependence.
- physiological dependence: symptoms that occur in response to the frequent presence of a drug,
esp. tolerance and withdrawal
- psychological dependence: cluster of cognitive, behavioural and physiological symptoms
occurring in one who continues to use a substance despite significant use-related problems
- NOTE: both are so intertwined that the two cannot be separated (i.e. for everyone
psychological state, there is a corresponding physiological one)
4. Name the anatomical regions of the limbic system that play a role in addiction.
- hippocampus, amygdala, nucleus accumbens, ventral tegmental area (VTA), prefrontal cortex
5. Describe the neurochemical effects of heroin on the brain.
- converted by enzymes to morphine once in the brain
- the morphine will bind to opioid receptors which stimulate increase in release of
neurotransmitter dopamine
- dopamine then activates other neurons and user experiences intense rush of pleasure
6. Explain the neurochemical changes that contribute to the development of tolerance.
- some drugs cause over stimulation of the nucleus accumbens through repeated release of
- this causes the nucleus accumbens to decrease the number of dopamine receptors it has (down-
regulation); since there a less dopamine receptors, there requires more dopamine is required to
produce the same effect (need to stimulate more release by more drug!)
- another way that tolerance develops is in altering the cell’s response to the drug
- when drug binds to cell, activates signal pathway, e.g. involving the enzyme adenylyl cyclise,
which causes cell to maintain its activity
- after repeated activation, adenylyl cyclise adapts; need more of the drug to stimulate the cell
7. What does “nurturing through avoidance” mean?
- nurturing through avoidance: repeatedly seeking the illusion of relief to avoid unpleasant
feelings or situations

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8. Describe the four common symptoms of addictions.
- compulsion: obsession or excessive preoccupation with the behaviours or drug
- loss of control: the inability to predict reliably whether any isolated occurrence of the
behaviours or use of a drug will be healthy or damaging
- negative consequences: e.g. physical damage, legal trouble, financial problems, academic
failure, relationship difficulties
- denial: the inability to perceive that the behaviours or druge use are self-destructive
9. List the different methods of administering drugs. For which methods are the effects
felt most rapidly?
- oral ingestion: need to pass through digestive system, so relatively slow absorption
- injection: intravenous injection results in extremely effective administration; intramuscular
injection results in much slower (hypodermic needle usually into buttocks or triceps);
subcutaneous injection puts drug into layer of fat directly beneath skin
- inhalation: ingestion of drugs through the nostrils; instantaneous effects but do not last long
(only small amounts can be absorbed and metabolized in the lungs)
- inunction: drugs into body through the skin; patches slowly release chemicals for a consistent
- suppositories: drugs mixed with a waxy medium that are designed to melt at body temperature
(inserted into the anus past the rectal sphincter muscles; wax melts and drug is released and
absorbed through rectal walls into bloodstream)
10. Define the following terms: synergism (a.k.a. potentiation), antagonism, inhibition,
intolerance, and cross-tolerance.
- synergism (potentiation): an interaction of two or more drugs in which the effects of the
individual drugs are multiplied beyond what is normally expected
- antagonism: one drug blocks the action of the other at the receptor site; symptoms are usually
not as serious as synergism
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