LIPPINCOTT ANS Flashcards
3.1 Which of the following is correct regarding the autonomic
nervous system (ANS)?
A. Afferent neurons carry signals from the CNS to the
effector organs.
B. The neurotransmitter at the parasympathetic
ganglion is norepinephrine (NE).
C. The neurotransmitter at the sympathetic ganglion is
acetylcholine (ACh).
D. Sympathetic neurons release ACh in the effector
organs.
E. Parasympathetic neurons release NE in the effector
organs.
Correct answer = C. The neurotransmitter at the sympathetic
and parasympathetic ganglia is acetylcholine. Sympathetic
neurons release NE and parasympathetic neurons release
ACh in the effector cells. Afferent neurons carry signals
from the periphery to the CNS.
3.2 Which of the following is correct regarding somatic motor
neurons?
A. The neurotransmitter at the somatic motor neuron
ganglion is acetylcholine.
B. The neurotransmitter at the somatic motor neuron
ganglion is norepinephrine.
C. Somatic motor neurons innervate smooth
muscles.
D. Somatic motor neurons do not have ganglia.
E. Responses in the somatic motor neurons are
generally slower than in the autonomic nervous
system.
Correct answer = D. Somatic motor neurons innervate skeletal
muscles (not smooth muscle) and have no ganglia.
Answers A and B are incorrect, since there are no ganglia.
Also, the responses in the somatic motor nervous system
are faster compared to the responses in the autonomic
nervous
system due to the lack of ganglia in the former.
3.3 Which of the following physiological changes could
happen when a person is attacked by a grizzly
bear?
A. Increase in heart rate.
B. Increase in lacrimation (tears).
C. Constriction of the pupil (miosis).
D. Increase in gastric motility.
Correct answer = A. When a person is in the “fight-or-flight”
mode, as in the case of a bear attack, the sympathetic
system
will be activated. Activation of the sympathetic system
causes an increase in heart rate and blood pressure
and a decrease (not increase) in gastric motility. It also
causes dilation (not constriction) of the pupil and inhibition
of lacrimation.
3.4 Which of the following changes could theoretically
happen in a person when the parasympathetic system is
inhibited using a pharmacological agent?
A. Reduction in heart rate.
B. Constriction of the pupil (miosis).
C. Increase in gastric motility.
D. Dry mouth (xerostomia).
E. Contraction of detrusor muscle in the bladder.
Correct answer = D. Activation of the parasympathetic
system
causes a reduction in heart rate, constriction of
the pupil, an increase in gastric motility and salivation, and
contraction of the bladder muscle. Therefore, inhibition of
the parasympathetic system causes an increase in heart
rate, dilation of the pupil, a decrease in gastric motility, dry
mouth, and relaxation of detrusor muscles.
3.5 Which of the following statements is correct regarding
the sympathetic and parasympathetic systems?
A. Acetylcholine activates muscarinic receptors.
B. Acetylcholine activates adrenergic receptors.
C. Norepinephrine activates muscarinic receptors.
D. Activation of the sympathetic system causes a drop
in blood pressure.
Correct answer = A. Acetylcholine is the neurotransmitter in
the cholinergic system, and it activates both muscarinic and
nicotinic cholinergic receptors, not adrenergic receptors.
Norepinephrine activates adrenergic receptors, not muscarinic
receptors. Activation of the sympathetic system causes
an increase in blood pressure (not a drop in blood pressure)
due to vasoconstriction and stimulation of the heart.
3.6 Which of the following statements concerning the
parasympathetic nervous system is correct?
A. The parasympathetic system uses norepinephrine
as a neurotransmitter.
B. The parasympathetic system often discharges as a
single, functional system.
C. The parasympathetic division is involved in
accommodation of near vision, movement of food,
and urination.
D. The postganglionic fibers of the parasympathetic
division are long compared to those of the
sympathetic nervous system.
E. The parasympathetic system controls the secretion
of the adrenal medulla.
Correct answer = C. The parasympathetic nervous system
maintains essential bodily functions, such as vision,
movement of food, and urination. It uses acetylcholine, not
norepinephrine, as a neurotransmitter, and it discharges
as discrete fibers that are activated separately. The postganglionic
fibers of the parasympathetic system are short
compared to those of the sympathetic division. The adrenal
medulla is under the control of the sympathetic system.
3.7 Which of the following is correct regarding neurotransmitters
and neurotransmission?
A. Neurotransmitters are released from the
presynaptic nerve terminals.
B. Neurotransmitter release is triggered by the arrival
of action potentials in the postsynaptic cell.
C. Intracellular calcium levels drop in the neuron
before the neurotransmitter is released.
D. Serotonin and dopamine are the primary
neurotransmitters in the ANS.
Correct answer = A. Neurotransmitters are released from
presynaptic neurons, triggered by the arrival of an action
potential in the presynaptic neuron (not in the postsynaptic
cell). When an action potential arrives in the presynaptic
neuron, calcium enters the presynaptic neuron and the calcium
levels increase in the neuron before the neurotransmitter
is released. The main neurotransmitters in the ANS
are norepinephrine and acetylcholine.
3.8 An elderly man was brought to the emergency room
after he ingested a large quantity of carvedilol tablets,
a drug that blocks α1, β1, and β2 adrenergic receptors,
which mainly mediate the cardiovascular effects of
epinephrine and norepinephrine in the body. Which of
the following symptoms would you expect in this patient?
A. Increased heart rate (tachycardia).
B. Reduced heart rate (bradycardia).
C. Dilation of the pupil (mydriasis).
D. Increased blood pressure.
Correct answer = B. Activation of α1 receptors causes
mydriasis, vasoconstriction, and an increase in blood pressure.
Activation of β1 receptors increases heart rate, contractility
of the heart, and blood pressure. Activation of β2
receptors causes dilation of bronchioles and relaxation of
skeletal muscle vessels. Thus, inhibition of these receptors
will cause vasorelaxation (α1 blockade), reduction in heart
rate (β1 blockade), reduction in contractility of the heart
(β1 blockade), reduction in blood pressure, bronchoconstriction
(β2 blockade), and constriction of blood vessels supplying
skeletal muscles (β2 blockade).
3.9 All of the following statements regarding central control
of autonomic functions are correct except:
A. Baroreceptors are pressure sensors located at
various cardiovascular sites.
B. The parasympathetic system is activated by the
CNS in response to a sudden drop in blood pressure.
C. The parasympathetic system is activated by the
CNS in response to a sudden increase in blood
pressure.
D. The sympathetic system is activated by the CNS in
response to a sudden drop in blood pressure.
Correct answer = B. When there is a sudden drop in blood
pressure, the baroreceptors send signals to the brain, and
the brain activates the sympathetic system (not the parasympathetic
system) to restore blood pressure to normal
values.
3.10 Which of the following is correct regarding membrane
receptors and signal transduction?
A. ANS neurotransmitters bind to membrane receptors
on the effector cells, which leads to intracellular
events.
B. Cholinergic muscarinic receptors are examples of
ionotropic receptors.
C. Cholinergic nicotinic receptors are examples of
metabotropic receptors.
D. Metabotropic receptors activate ion channels directly.
Correct answer = A. Neurotransmitters generally bind to the
membrane receptors on the postsynaptic effector cells and
cause cellular effects. Acetylcholine (ACh) binds to cholinergic
muscarinic receptors in the effector cells and activates
the second messenger pathway in the effector cells, which
in turn causes cellular events. These types of receptors that
are coupled to second messenger systems are known as
metabotropic receptors. Thus, metabotropic receptors do
not directly activate ion channels. ACh also binds to cholinergic
nicotinic receptors and activates ion channels on the
effector cells directly. These types of receptors that activate
ion channels directly are known as ionotropic receptors.
