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PHM 431 Exam 1 | Questions | With Complete Solutions
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PHM 431 Exam 1 | Questions | With Complete Solutions
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PHM 431 Exam 1 | Questions | With Complete Solutions-Emax
-Efficacy
-Potency Correct Answers -EC50 is the agonist concentration
needed to produce one half of the maximum response.
-Emax is the maximum effect.
- efficacy is a measure of the maximum response an agonist can
produce. The higher the max response the more efficacious a
drug is.
-Potency is a measure of the amount of agonist required to
produce a given level of response. This is usually measured at
the EC50 level. Drugs with lower EC50 values are more potent
than drugs with high EC50 values
5-HT Storage and Release Correct Answers Like Dopamine
and Norepinephrine, Serotonin is synthesized in the cytoplasm
of the nerve terminal and pumped into vesicles by the vesicular
monoamine transporter (VMAT). After release, it is taken by up
by the high affinity transport SERT. 5-HT can also be
metabolized by MAO. When this occurs, serotonin is degraded
to 5-hydroxyindoleacetic acid or 5-HIAA.
5-HT Synthesis Correct Answers -Serotonin is synthesized
from tryptophan by the action of tryptophan hydroxylase to
produce 5- hydroxytryptophan. The availability of tryptophan is
the rate limiting factor in serotonin synthesis. 5-
hydroxytryptophan is then converted to 5-Hydroxytryptamine or
Serotonin by the enzyme aromatic amino acid decarboxylase
(Figure 10).
,-In the pineal gland, serotonin is converted to melatonin, which
plays a role in circadian rhythms and the sleep wake cycle.
Absorption Correct Answers -Absorption is the process by
which drug molecules reach the plasma from the original site of
administration.
-All routes of drug administration, except for IV administration,
require the drug to pass through cytoplasm and membranes of
various cells to get to the plasma (circulation).
-Absorption rates depend on:
• Surface area of the absorption surface •Vascularization (the
number of blood vessels draining the drug administration site)
• Blood flow to the site of absorption (the number of blood
vessels supplying the site)
-There are several mechanisms of drug absorption but passive
diffusion is the most common and important.
Acetylation is an example of which of the following drug
metabolism reactions?
A)Cyt-P450 induction
B)Phase 2 conjugation reaction.
C)Increased lipophilicity
D)Albumin conjugation Correct Answers b
Acquired Tolerance Correct Answers tolerance that develops
subsequent to drug administration (3 types)
1) Pharmacokinetic tolerance - changes in drug sensitivity due
to changes in the distribution or metabolism of the drug. Alcohol
can induce enzymes responsible for detoxification, barbiturates
induce cytochrome P450 responsible for metabolism.
,2) Pharmacodynamic tolerance - adaptive changes in the system
in response to repeated drug administration. Receptor down-
regulation, or down regulation of effector molecules activated
by the receptor.
3) Learned tolerance - skills developed through experience with
drugs. Common with alcohol abuse and can also occur with non-
abused drugs.
Action Potential Propagation Correct Answers -Actions
potentials propagate along the axon towards the nerve terminal
(Figure 11). This occurs due to sequential movements of the
depolarization and sequential opening and closing of sodium
channels in the axon.
-When the axon is depolarized, the sodium channels open
causing a depolarization of nearby sodium channels. When these
nearby sodium channels open, the action potential moves further
down the axon toward the terminals. The sodium channels cycle
from 1) closed, to 2) open following depolarization from the
action potential, to 3) inactivated once the action potential has
passed, and then 4) back to a closed state (Figure 12).
-Some axons are wrapped by a myelin sheath, which is
composed primarily of lipids (Figure 13). This wrapping
increases the resistance of the axon and increases the speed of
conduction down the axon because it prevents the loss of sodium
ions from the axon. In myelinated axons, the action potential
does not propagate as a wave but rather jumps from one node of
ranvier to the next. This is called Saltatory Conduction (Figure
14). The nodes of ranvier are gaps in the myelination that
contain a high number of sodium channels. The loss of
myelination is a hallmark of some neurodegenerative diseases,
such as multiple sclerosis.
, Addictive drugs Correct Answers -legal (alcohol, cigarettes,
and some prescription drugs)
-illegal drugs (heroin,
methamphetamine)
Adolescent drug use is a risk factor for a lifelong drug problem.
Why is this the case?
A)Adolescents metabolize drugs very slowly, so higher blood
levels of drugs are achieved and this increases the reward
associated with drug use.
B)The elimination rates of drugs are slower in adolescents
allowing higher blood levels of drugs to be achieved.
C)The prefrontal cortex (PFC) is a key decision making part of
the brain, it is a target for addictive drugs and it is a late
maturing part of the brain.
D)All of the above Correct Answers c
agonist Correct Answers An agonist is any molecule that binds
to a receptor and activates that receptor to cause a response.
Alpha-methyl tyrosine is an inhibitor of tyrosine hydroxylase.
Treatment of mice with this drug would be expected to cause:
A)
Depletion of neurotransmitter content in the locus ceruleus
B)
Depletion of neurotransmitter content in the dorsal raphe
nucleus
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