Pharm Autonomics W Exp Part 1

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.

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.

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

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.

Activation of the M2 receptor leads to decreased AV conduction.

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.

not-available-via-ai

The activation of the Beta-2 receptor leads to increased gluconeogenesis.

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.

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.

not-available-via-ai

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.

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.

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. .

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

not-available-via-ai

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.

Activation of the D-1 receptor leads to selective dilation of renal vessels.

Blockade of the M3 receptor can lead to decreased aqueous humor outflow.

not-available-via-ai