Each of the following types of receptors is correctly matched with the response resulting from its stimulation EXCEPT:

Correct Answer: B

Rationale: The correct answer is B. Nicotinic receptors are not associated with decreased gastric acid secretion, but rather with muscle contraction at neuromuscular junctions. A: Muscarinic receptors stimulation leads to decreased heart rate via parasympathetic activation. C: Activation of alpha adrenergic receptors causes vasoconstriction and increased blood pressure. D: Stimulation of beta adrenergic receptors results in bronchodilation and increased heart rate. Therefore, choice B is the exception as it does not match the typical response of nicotinic receptors.

Correct Answer: D

Rationale: The correct answer is D: Stimulate uterine contraction. Selective β2 agonists primarily target β2 receptors in the lungs, leading to bronchodilation. They have minimal effect on β1 receptors, thus do not significantly impact heart rate or blood pressure. However, β2 receptors in the uterus can cause uterine relaxation, not contraction. Therefore, selective β2 agonists do not stimulate uterine contractions. Choices A, B, and C are incorrect as they align with the typical effects of selective β2 agonists.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Adrenaline is not given orally because: A) It is inactivated in the gut mucosa due to enzymatic breakdown, B) Local vasoconstriction inhibits absorption into the bloodstream, and C) It is rapidly inactivated in circulation by enzymes like catechol-O-methyltransferase and monoamine oxidase. Therefore, administering adrenaline orally would result in poor absorption and rapid degradation, making it ineffective.

Correct Answer: C

Rationale: Correct Answer: C Rationale: 1. Phenylephrine is a vasoconstrictor that raises blood pressure. 2. Increased blood pressure activates the baroreceptor reflex. 3. Baroreceptor reflex detects elevated blood pressure and sends signals to the brain. 4. The brain then signals the heart to slow down, thus normalizing the rapid heart rate in PSVT. Summary: A: Blocking beta-receptors would have the opposite effect, as beta-blockers slow down the heart rate. B: Stimulating norepinephrine release would increase heart rate, not slow it down. D: ACh esterase is involved in the breakdown of acetylcholine, not relevant to the mechanism of action of phenylephrine in PSVT.

Correct Answer: A

Rationale: Rationale: Atropine is the correct answer as it is an anticholinergic agent like propantheline, both inhibiting acetylcholine activity. This action reduces gastric acid secretion, aiding in peptic ulcer treatment. Neostigmine (B) increases acetylcholine activity, opposite to propantheline's effect. Propranolol (C) is a beta-blocker, not directly affecting gastric acid secretion. Phentolamine (D) is an alpha-blocker, also not related to reducing gastric acid secretion.