PSYC 450 Drugs and Behaviour – final exam Study
practice Questions and answers complete exam
solution Athabasca University
, PSYC 450 Drugs and Behaviour – final exam Study practice Questions and answers complete exam
solution Athabasca University
Define "psychopharmacology." - CORRECT ANSWER The study of drug effects on psychological states
and symptoms. Emphasizes drug-induced changes in mood, thinking and behaviour.
What is meant by the term "pharmacokinetics"? - CORRECT ANSWER Pharmacokinetics is the process
by which drugs are absorbed, distributed within the body, metabolized, and excreted.
Bioavailability, which is a measure of the extent of drug absorption for a given drug and route (from
0% to 100%) is related to pharmacokinetics. The factors which contribute to bioavailability constitute
the pharmacokinetic component of drug action:
1. Routes of administration: how and where the drug is administrated determines how quickly and
completely it is absorbed into the blood.
2. Absorption and distribution: a drug rarely acts where it initially contacts the body, and so it must
pass through a variety of cell membranes and enter the blood plasma, which transports the drug to
virtually all of the cells in the body.
3. Binding: once in the blood plasma, some drug molecules move to tissues to bind to active target
sites (receptors). While in the blood, a drug may also bind (depot binding) to plasma proteins or may
be stored temporarily in bone or fat, where it is inactive.
4. Inactivation: drug inactivation or biotransformation, occurs primarily as a result of metabolic
processes in the liver. The amount of drug in a system depends on the relationship between
absorption and inactivation.
5. Excretion: the liver metabolites are eliminated from the body with the urine or feces. Some drugs
are excreted in an unaltered form by the kidneys.
Describe the advantages and disadvantages of intravenous injection. - CORRECT ANSWER Advantages:
- The most rapid and accurate form of drug administration.
Disadvantages:
,- The quick onset of drug effect with IV injection is potentially hazardous.
- An overdose or allergy leaves little time for corrective measures.
- Produces a more intense subjective drug experience since the drug reaches the brain almost
instantly.
- When used with street drugs, impure drugs can lead to toxic reactions and equipment that isn't
sterile can cause infections.
What are lipid-soluble drugs? - CORRECT ANSWER Drugs with high lipid solubility move through cell
membranes by passive diffusion, leaving the water in the blood or stomach juices and entering the
lipid layers of membranes. Movement across the membranes is always in a direction from higher to
lower concentration. The larger the concentration difference on each side of the membrane (called
the concentration gradient), the more rapid the diffusion. Lipid solubility increases the absorption of
the drug into the blood and determines how readily a drug will pass the lipid barriers to enter the
brain. For example, the narcotic drug heroin is a simple modification of the parent compound
morphine. Heroin is more soluble in lipid than morphine, and it penetrates into brain tissue more
readily, this having a quicker onset of action and more potent reinforcing properties. This occurs
despite the fact that before the psychotropic drug effects occur, the heroin must be converted to
morphine by esterase enzymes in the brain. That property makes heroin a prodrug, that is, one that is
dependent, on metabolism to convert an active drug to an active one, a process called bioactivation.
This strategy is one used by pharmaceutical companies that develop prodrugs that cross the blood-
brain barrier if the active drug cannot penetrate easily.
Explain the importance of the blood-brain barrier. - CORRECT ANSWER 1. Protects the brain from
"foreign substances" in the blood that may injure the brain.
2. Protects the brain from neurotransmitters in the rest of the body.
3. Maintains a constant environment for the brain.
Define "half-life." - CORRECT ANSWER The time required for the amount of drug in the body to
decrease by 50%. For example, if the half-life is one day, in 1 day, 50% is left; in 2 days, 25% is left; in 3
days, 12.5% is left; etc.
, What is meant by the term "pharmacodynamics"? - CORRECT ANSWER The study of the biochemical
and physiologic effects of drugs on the function of living organisms and their component parts (how it
works in the body).
What are receptors? What are ligands? - CORRECT ANSWER Receptor: any functional macromolecule
in a cell to which a drug binds to produce its effects.
Ligands: any molecule that binds to a receptor with some selectivity.
Describe how receptors can be modified. In other words, explain the life-cycle of receptors. - CORRECT
ANSWER There are two principal types of receptors:
1. Most drugs and neurotransmitters remain outside the cell and bind to receptors on the exterior cell
surface. When these receptors are activated, they initiate changes in an effector, causing intracellular
changes such as the movement of ions or changes in enzyme activity.
Many hormones are capable of entering the cell before acting on an intracellular receptor that
changes the expression of specific genes within the nucleus. The altered protein synthesis in turn
leads to changes in cell function that may include altering gluconeogenesis, modulation of the
menstrual cycle and others.
2. The second type of receptor is found within the target cell, either in the cytoplasm or in the
nucleus. Most of the hormones that act on the brain to influence neural events use this type of
receptor. Hormonal binding to intracellular receptors alters cell function by triggering changes in the
expression of genetic material within the nucleus, producing changes in protein synthesis. Sex
hormones act in this way to facilitate mating behaviour and other activities related to reproduction,
such as lactation.
Differentiate between tolerance and sensitization. - CORRECT ANSWER Tolerance: refers to the
decreased effectiveness of a given drug with repeated administration.
Sensitization: refers to the increased effectiveness with repeated administration.
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