1.
Match each effect with the activation of the appropriate receptor (each lettered option can be
selected once, more than once, or not at all):
Mydriasis
Correct Answer
A. AlpHa-1
2.
Match each effect with the activation of the appropriate receptor (each lettered option can be
selected once, more than once, or not at all):
Increased gluconeogenesis
Correct Answer
D. Beta-2
Explanation
The activation of the Beta-2 receptor leads to increased gluconeogenesis.
3.
Match each effect with the activation of the appropriate receptor (each lettered option can be
selected once, more than once, or not at all):
Selective dilation of renal vessels
Correct Answer
F. D-1
Explanation
Activation of the D-1 receptor leads to selective dilation of renal vessels.
4.
Match each effect with the activation of the appropriate receptor (each lettered option can be
selected once, more than once, or not at all):
Constriction of bladder internal sphincter
Correct Answer
A. AlpHa-1
Explanation
The correct answer is Alpha-1. The constriction of the bladder internal sphincter is mediated by the activation of the Alpha-1 receptors. These receptors are found in smooth muscle cells and their activation leads to vasoconstriction and contraction of smooth muscles. In the case of the bladder internal sphincter, the activation of Alpha-1 receptors causes its constriction, preventing the flow of urine from the bladder into the urethra.
5.
Match each effect with the activation of the appropriate receptor (each lettered option can be
selected once, more than once, or not at all):
Decreased AV conduction
Correct Answer
H. M2
Explanation
Activation of the M2 receptor leads to decreased AV conduction.
6.
Directions: questions 6-10
Match each effect with the blockade of the appropriate receptor (each lettered option can be
selected once, more than once, or not at all):
Mydriasis
Correct Answer
I. M3
7.
Match each effect with the blockade of the appropriate receptor (each lettered option can be
selected once, more than once, or not at all):
Decreased aqueous humor outflow
Correct Answer
I. M3
Explanation
Blockade of the M3 receptor can lead to decreased aqueous humor outflow.
8.
Match each effect with the blockade of the appropriate receptor (each lettered option can be
selected once, more than once, or not at all):
Tachycardia
Correct Answer
H. M2
9.
Match each effect with the blockade of the appropriate receptor (each lettered option can be
selected once, more than once, or not at all):
Relaxation of bladder external sphincter
Correct Answer
J. Nm
10.
Match each effect with the blockade of the appropriate receptor (each lettered option can be
selected once, more than once, or not at all):
Decreased intestinal peristalsis
Correct Answer
I. M3
Explanation
Blockade of the M3 receptor would result in decreased intestinal peristalsis. The M3 receptor is primarily found in smooth muscle, including the smooth muscle of the gastrointestinal tract. Activation of the M3 receptor promotes contraction of smooth muscle, including the muscles responsible for peristalsis in the intestines. Therefore, blocking the M3 receptor would lead to a decrease in intestinal peristalsis.
11.
Which of the following fibers of the peripheral nervous system are short and
unmyelinated?
Correct Answer
A. Postganglionic parasympathetic
Explanation
Answer: A
Postganglionic fibers of the ANS are all unmyelinated. Those of the parasympathetic nervous
system are short.
B) Postganglionic sympathetic fibers are usually long.
C, D, E, F) All these fibers are myelinated
12.
Fibers of the sympathetic nervous system that utilize acetylcholine as postganglionic
neurotransmitter innervate which of the following tissues/organs?
Correct Answer
C. Sweat glands
Explanation
Answer: C
The vast majority of sweat glands in the body are innervated by sympathetic cholinergic
neurons, i.e. sympathetic postganglionic neurons that happen to release acetylcholine instead
of norepinephrine.
B, C, D, E , F) All these tissues/organs do not have sympathetic cholinergic innervation.
13.
Which of the following is the predominant mechanism that terminates the action of the
main neurotransmitter released by postganglionic adrenergic nerve endings?
Correct Answer
E. Reuptake into the nerve ending
Explanation
Answer: E
The termination of action of norepinephrine released from the adrenergic nerve ending, mainly
occurs by reuptake of the neurotransmitter into the adrenergic terminal.
A, B, C) These mechanisms may contribute to the termination of action, but are secondary
mechanisms.
D, F) These mechanisms are not involved in the termination of action of norepinephrine.
14.
Which of the following is a site where autonomic receptors are primarily Nn
cholinergic?
Correct Answer
A. Celiac ganglion
Explanation
Answer: A
The celiac ganglion is a sympathetic ganglion. In all autonomic ganglia receptors are primarily
Nn.
B) Autonomic receptors in gall bladder are primarily M3.
C) Autonomic receptors in sinoatrial node are primarily M2.
D) Autonomic receptors in vascular smooth muscle are primarily alpha-1 and beta-2.
E) Autonomic receptors in the lower esophageal sphincter are primarily M3.
15.
Which of the following effects is most likely mediated by the activation of peripheral
postsynaptic beta-1 receptors?
Correct Answer
B. Increased synthesis of angiotensin II
Explanation
Answer: B
Activation of beta-1 receptors increases renin secretion. Renin is the enzyme that catalyzes the
biosynthesis of angiotensin II.
A) Activation of beta-1 receptors increases heart contractility and rate. This would cause
coronary vasodilation, not vasoconstriction.
C) The increase in intestinal peristalsis is mainly mediated by the activation of M3 receptors.
D) The increase in gluconeogenesis is mediated by the activation of beta-2 receptors
E) The beta-1 receptor mediated increase in heart contractility and rate would increase, not
decrease, the blood pressure.
16.
Which of the following is the predominant mechanism that terminates the action of the
main neurotransmitter released by preganglionic nerve endings?
Correct Answer
D. Metabolism by acetylcholinesterase
Explanation
Answer: D
The main neurotransmitter released by preganglionic nerve endings (both sympathetic and
parasympathetic) is acetylcholine which, when released into the synaptic cleft, is quickly
metabolized by acetylcholinesterase. This is the main mechanism that terminates the action of
acetylcholine.
A) This enzyme catalyze the synthesis, not the metabolism, of acetylcholine.
B) This enzyme catalyze the metabolism of catecholamines.
C, E) These mechanisms are not involved in the termination of the action of acetylcholine. .
17.
Which of the following actions most likely results from the activation of autonomic
autoreceptors?
Correct Answer
A. Modulation of neurotransmitter release
Explanation
Answer: A
A receptors is defined “autoreceptor” when it modulates the release of the neurotransmitter
that activates it. In most cases this modulation results in an inhibition of the release (alpha-2
autoreceptors inhibit the release of norepinephrine, M2 autoreceptors inhibit the release of
acetylcholine) but in a few cases there is a stimulation of the release (beta-2 autoreceptors
stimulate the release of norepinephrine, Nn autoreceptors stimulate the release of
acetylcholine).
B, C, D, E) Autonomic autoreceptors are not involved in the synthesis, storage or reuptake of a
neurotransmitter
18.
Which of the following is a site where autonomic receptors are primarily alpha-1
adrenergic?
Correct Answer
E. Skin vessels
Explanation
Answer: E
The vascular system has both alpha-1 and beta-2 receptors. Alpha-1 receptors predominate in
the vessels of the skin, gastrointestinal system and genitourinary system. Beta-2 receptors
predominate in the vessels of skeletal muscle and liver. Parasympathetic receptors are not
widely represented in the vascular system.
A) Autonomic receptors in the bronchial muscle are primarily M3 and beta-2.
B) Autonomic receptors in the sphincter muscle of iris the are primarily M3.
C) Autonomic receptors in the atrioventricular node are primarily M2 and beta-1.
D) Autonomic receptors in Purkinje’s fibers are primarily beta-1.
19.
Which of the following is a site where autonomic receptors are primarily alpha-2
adrenergic?
Correct Answer
E. Platelets
Explanation
Answer: E
Platelets have alpha-2 receptors that can stimulate platelet aggregation. These receptors are
not innervated but the increased plasma concentration of epinephrine and norepinephrine
during the activation of the sympathetic nervous system increases the aggregation of platelet so
improving the hemostasis. This is a good outcome in emergency situations since it helps
limiting bleeding from wounds.
A, B, C,) The autonomic receptors in these locations are primarily M3.
D) Somatic receptors in skeletal muscle are primarily Nm. Autonomic receptors in skeletal
muscle are primarily alpha-1 and beta-2.
20.
Which of the following is a site where autonomic receptors are primarily beta-1
adrenergic?
Correct Answer
D. Juxtaglomerular cells
Explanation
Answer: D
Beta-1 receptors are abundant in juxtaglomerular cells and the activation of these receptors
increases renin secretion.
A) Autonomic receptors in gastric parietal cells are primarily M 3.
B) Autonomic receptors in the radial muscle of iris are primarily alpha-1.
C) Autonomic receptors in the internal sphincter of the bladder are likely peptide receptors
E) Autonomic receptors in the beta cells of the pancreas are primarily alpha-2.