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: In pharmacology, understanding the absorption of drugs is crucial for predicting their efficacy and potential side effects. In the case of hydrochlorothiazide, a diuretic commonly used to treat hypertension, its main site of absorption is the small intestine. The small intestine is the primary site of drug absorption in the digestive tract due to its large surface area, which is ideal for efficient absorption of hydrophilic drugs like hydrochlorothiazide. The presence of villi and microvilli further increases the absorptive surface area, allowing for better drug uptake into the bloodstream. Option A, the oral mucosa, is not the main site of absorption for hydrochlorothiazide as it is primarily absorbed in the gastrointestinal tract. The stomach (Option B) is not an ideal site for drug absorption due to its acidic environment and limited surface area compared to the small intestine. The colon (Option D) is mainly responsible for water and electrolyte absorption rather than drug absorption. Educationally, understanding the specific absorption sites of drugs in the digestive tract is essential for pharmacology students and healthcare professionals to optimize drug therapy and anticipate potential drug interactions or variations in drug effects based on the route of administration. This knowledge enhances clinical decision-making and patient care outcomes.

Correct Answer: A

Rationale: In pharmacology, understanding the mechanisms of drug absorption is crucial for predicting their effects. In this case, the correct answer is A) Aqueous diffusion. Ethanol, being a small and hydrophilic molecule, is able to passively diffuse through the aqueous channels in the intestinal epithelium. This process does not require energy input and is driven by concentration gradients, making it the primary mechanism for ethanol absorption. Bulk flow transport (B) involves the movement of substances in fluid along with the flow, which is not the case for ethanol absorption. Facilitated diffusion (C) and active transport (D) both require specific carrier proteins and energy input, which are not involved in ethanol absorption. Educationally, understanding the different mechanisms of drug permeation is essential for predicting drug bioavailability and efficacy. By grasping the concept of aqueous diffusion in drug absorption, students can appreciate how different drug properties influence their absorption rates and ultimately their therapeutic effects. This knowledge is foundational for pharmacology students to make informed decisions in drug development and patient care.