NST 11 MIDTERM 1 EXAM QUESTIONS
WITH COMPLETE SOLUTIONS
Can xenobiotics and other less toxic substances modulate the expression and
activities of xenobiotic metabolism enzymes? - ANSWER-yes
What does a "drink" means?
What percentage of alcohol enter bloodstream and how does food affect alcohol
absorption?
How does alcohol distribute itself? - ANSWER-A standard alcoholic "drink" consists
of 10 grams of ethanol. This amount is equal to 10 ounces (300 ml) of regular beer
(5% alcohol content); 3-4 ounces of wine (12% alcohol content); or 1 ounce of hard
liquor (40% alcohol content, 80 "proof").
Approximately 20% of ethanol is absorbed into the bloodstream directly from the
stomach, and 80% from the small intestine.
Food (especially slow-digesting) decreases alcohol absorption.
Distribution: Ethanol is highly soluble in water and is absorbed much less into fat. So
alcohol tends to distribute itself mostly in tissues rich in water (muscle) instead of
those rich in fat. (women, elderly more sensitive)
What is the mode of alcohol action? - ANSWER-Alcohol increases the effect of the
body's naturally occurring inhibitory neurotransmitter, GABA (gamma amino butyric
acid).
Exposure to ethanol and other intoxicant-anesthetics activate GABA-stimulated
chloride channels and inhibit voltage-dependent calcium and sodium channels of
brain membranes.
Ethanol reduces nerve signal flow in the brain. By way of comparison, cocaine does
the opposite by producing a general excitatory effect on the nervous system
What is the anatomy of nervous system cells? - ANSWER-look at image on
computer
What are the steps of neurotransmission? - ANSWER--Synthesis of neurotransmitter
in the presynapse
-Storage of the neurotransmitter in secretory vesicles
-Regulated release of neurotransmitter into the synaptic space.
-The binding of released neurotransmitters to post-synaptic receptors to propagate
neurotransmission.
-Binding of the transmitter to postsynaptic receptors is followed by modulation of an
ion channel or activation of a second messenger system, leading to changes in the
responding cell
-A means for terminating the action of the released neurotransmitter
, What is "synapses" and "neurotransmitters"? - ANSWER-synapse: specialized
junctions through which neurons signal to each other and to non-neuronal cells such
as those in muscles or glands.
Neurotransmitters released from the presynapse bind receptors on the post-synapse
to propagate the signal
What are three enzymes involved in alcohol metabolism? - ANSWER-Ethanol is
handled by two distinct chemical mechanisms in the body: 1) the dehydrogenase
enzymes, ADH (alcohol dehydrogenase) and ALDH (aldehyde dehydrogenase),
which occur in many tissues, and 2) the microsomal (endoplasmic reticulum) ethanol
oxidizing system (MEOS/CYP2E1), located in the liver.
ADH ALDH2
Ethanol -----> acetaldehyde (toxic) ------> acetic acid
CYP2E1 CYP2E1
What is the genetic basis of flushed faces in alcohol drinking?
Why northeastern Asians are prone to develop esophageal cancer, whereas other
population is prone to develop alcoholism? - ANSWER-Symptoms of flushed face
and extreme nausea occur even with very low levels of alcohol in members of certain
races, especially Asians, due to a relative lack of systemic ALDH2. There are two
isoforms of ALDH2. Most Europeans have these two isozymes, while approximately
50% of Northeast Asians have one normal and one mutant copy of ALDH2-2. These
results in the accumulation of acetaldehyde in body that causes redness of face and
flush. The population with normal ALDH-2 are prone to develop alcoholism, whereas
those with one mutant copy of ALDH2 are prone to develop esophageal cancer.
Can drinking more alcohol increase our body to metabolize more alcohol? -
ANSWER-Habitual drinking induces CYP2E1 activity
Why is using alcohol and Valium together is dangerous? - ANSWER-Combined
exposures of sedatives, e.g. Valium, with ethanol can be lethal because of a
combined synergistic mode of action on GABA action.
-both are depressants, increasing GABA, which decreases Calcium, which
decreases activity in the brain, and that can be lethal when combined
What is the legal limit of blood alcohol content? - ANSWER-.08%
Can we prove any chemical compound that is absolutely safe?
What is certain safety factor? - ANSWER-Absolute safety impossible to prove
MS (Certain Safety Factor) = LD1/ED99
What factors we use to calculate "risk"? - ANSWER-Hazard. "Intrinsic toxic
properties."
-(In vitro and in vivo tests, SAR:Structure and activity relationship, epidemiology)
Dose-Response Assessment.
-(LD50, TD50, species differences, etc)
WITH COMPLETE SOLUTIONS
Can xenobiotics and other less toxic substances modulate the expression and
activities of xenobiotic metabolism enzymes? - ANSWER-yes
What does a "drink" means?
What percentage of alcohol enter bloodstream and how does food affect alcohol
absorption?
How does alcohol distribute itself? - ANSWER-A standard alcoholic "drink" consists
of 10 grams of ethanol. This amount is equal to 10 ounces (300 ml) of regular beer
(5% alcohol content); 3-4 ounces of wine (12% alcohol content); or 1 ounce of hard
liquor (40% alcohol content, 80 "proof").
Approximately 20% of ethanol is absorbed into the bloodstream directly from the
stomach, and 80% from the small intestine.
Food (especially slow-digesting) decreases alcohol absorption.
Distribution: Ethanol is highly soluble in water and is absorbed much less into fat. So
alcohol tends to distribute itself mostly in tissues rich in water (muscle) instead of
those rich in fat. (women, elderly more sensitive)
What is the mode of alcohol action? - ANSWER-Alcohol increases the effect of the
body's naturally occurring inhibitory neurotransmitter, GABA (gamma amino butyric
acid).
Exposure to ethanol and other intoxicant-anesthetics activate GABA-stimulated
chloride channels and inhibit voltage-dependent calcium and sodium channels of
brain membranes.
Ethanol reduces nerve signal flow in the brain. By way of comparison, cocaine does
the opposite by producing a general excitatory effect on the nervous system
What is the anatomy of nervous system cells? - ANSWER-look at image on
computer
What are the steps of neurotransmission? - ANSWER--Synthesis of neurotransmitter
in the presynapse
-Storage of the neurotransmitter in secretory vesicles
-Regulated release of neurotransmitter into the synaptic space.
-The binding of released neurotransmitters to post-synaptic receptors to propagate
neurotransmission.
-Binding of the transmitter to postsynaptic receptors is followed by modulation of an
ion channel or activation of a second messenger system, leading to changes in the
responding cell
-A means for terminating the action of the released neurotransmitter
, What is "synapses" and "neurotransmitters"? - ANSWER-synapse: specialized
junctions through which neurons signal to each other and to non-neuronal cells such
as those in muscles or glands.
Neurotransmitters released from the presynapse bind receptors on the post-synapse
to propagate the signal
What are three enzymes involved in alcohol metabolism? - ANSWER-Ethanol is
handled by two distinct chemical mechanisms in the body: 1) the dehydrogenase
enzymes, ADH (alcohol dehydrogenase) and ALDH (aldehyde dehydrogenase),
which occur in many tissues, and 2) the microsomal (endoplasmic reticulum) ethanol
oxidizing system (MEOS/CYP2E1), located in the liver.
ADH ALDH2
Ethanol -----> acetaldehyde (toxic) ------> acetic acid
CYP2E1 CYP2E1
What is the genetic basis of flushed faces in alcohol drinking?
Why northeastern Asians are prone to develop esophageal cancer, whereas other
population is prone to develop alcoholism? - ANSWER-Symptoms of flushed face
and extreme nausea occur even with very low levels of alcohol in members of certain
races, especially Asians, due to a relative lack of systemic ALDH2. There are two
isoforms of ALDH2. Most Europeans have these two isozymes, while approximately
50% of Northeast Asians have one normal and one mutant copy of ALDH2-2. These
results in the accumulation of acetaldehyde in body that causes redness of face and
flush. The population with normal ALDH-2 are prone to develop alcoholism, whereas
those with one mutant copy of ALDH2 are prone to develop esophageal cancer.
Can drinking more alcohol increase our body to metabolize more alcohol? -
ANSWER-Habitual drinking induces CYP2E1 activity
Why is using alcohol and Valium together is dangerous? - ANSWER-Combined
exposures of sedatives, e.g. Valium, with ethanol can be lethal because of a
combined synergistic mode of action on GABA action.
-both are depressants, increasing GABA, which decreases Calcium, which
decreases activity in the brain, and that can be lethal when combined
What is the legal limit of blood alcohol content? - ANSWER-.08%
Can we prove any chemical compound that is absolutely safe?
What is certain safety factor? - ANSWER-Absolute safety impossible to prove
MS (Certain Safety Factor) = LD1/ED99
What factors we use to calculate "risk"? - ANSWER-Hazard. "Intrinsic toxic
properties."
-(In vitro and in vivo tests, SAR:Structure and activity relationship, epidemiology)
Dose-Response Assessment.
-(LD50, TD50, species differences, etc)
