Which one of the following is NOT a beta-blocker?

Correct Answer: A

Rationale: The correct answer is A: Amphetamine. Beta-blockers like Propranolol, Carvedilol, and Timolol work by blocking the effects of adrenaline on beta receptors, reducing heart rate and blood pressure. Amphetamine, on the other hand, is a stimulant drug that works by increasing the release of neurotransmitters like dopamine and norepinephrine, unrelated to beta receptor blockade. Therefore, Amphetamine is not a beta-blocker.

Correct Answer: B

Rationale: The correct answer is B: Increase of bronchial secretion. Parasympathetic stimulation activates the vagus nerve, leading to bronchial smooth muscle relaxation and increased secretion to facilitate breathing. This response helps in clearing the airways and optimizing gas exchange. Choices A, C, and D are incorrect because parasympathetic stimulation typically does not lead to an increase in intestinal motility (A), contraction of the iris sphincter muscle causing miosis (C), or a decrease in heart rate (D), as these are more characteristic of sympathetic stimulation.

Correct Answer: A

Rationale: Step 1: Nicotinic AChRs are ion channels that allow the passage of ions across the cell membrane in response to acetylcholine. Step 2: The ion channels are not protein-bound or slow, so option B is incorrect. Step 3: Nicotinic AChRs are not G-coupled receptors, so option C is incorrect. Step 4: Nicotinic AChRs are located on the cell membrane, making them water-soluble, so option A is correct. Step 5: Nicotinic AChRs are not intracellular receptors, so option D is incorrect.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.