Monoamine Oxydase A:

Correct Answer: A

Rationale: Step-by-step rationale: 1. Monoamine Oxidase A (MAO-A) is an enzyme responsible for metabolizing neurotransmitters such as norepinephrine, serotonin, and tyramine. 2. MAO-A specifically targets norepinephrine and serotonin, making choice A correct. 3. Choices B, C, and D are incorrect as they incorrectly describe the functions and selectivity of MAO-A. In summary, MAO-A is responsible for norepinephrine, serotonin, and tyramine metabolism, making choice A the correct answer.

Correct Answer: C

Rationale: The correct answer is C because sharp swings from a cheerful mood to an aggressive state are not typically associated with barbiturate intoxication. Barbiturates generally depress the central nervous system, leading to symptoms such as stupor, confusion, and slowed thinking. Choice A includes symptoms like vertigo and myasthenia, which can be experienced during barbiturate intoxication. Choice B includes symptoms like perceptual distortions, behavior changes, and speech excitation, which are commonly seen in barbiturate intoxication. Choice D mentions sleep with subsequent weakness and headaches, which are also common symptoms of barbiturate intoxication. Overall, the incorrect choices describe symptoms that align with barbiturate intoxication, making C the outlier.

Correct Answer: B

Rationale: The correct answer is B: Aethylmorphine hydrochloride. Antitussives of narcotic type act on the cough center in the brain to suppress cough reflex. Aethylmorphine is an opioid derivative that exerts its antitussive effect centrally. Glaucine hydrochloride (A) is a non-narcotic antitussive derived from plants. Tusuprex (C) is a non-narcotic antitussive that acts peripherally. Libexine (D) is an antihistamine, not an antitussive.

Correct Answer: B

Rationale: The correct answer is B because stimulant purgatives work by increasing motility and secretion in the intestines. This leads to enhanced peristalsis, resulting in the expulsion of fecal matter. Choice A is incorrect as stimulant purgatives do not directly affect the volume of non-absorbable solid residue. Choice C is incorrect as altering fecal consistency is not the primary mechanism of stimulant purgatives. Choice D is incorrect as stimulant purgatives primarily work by increasing motility and secretion, not the water content in the intestines.

Correct Answer: A

Rationale: Step 1: Digoxin inhibits the sodium-potassium pump, leading to an increase in intracellular sodium. Step 2: Increased intracellular sodium levels reduce the activity of the sodium-calcium exchanger. Step 3: Slowing down the sodium-calcium exchanger causes an increase in intracellular calcium levels in myocardial cells. Step 4: Therefore, the statement that digoxin increases intracellular calcium concentrations by slowing the action of the sodium-calcium exchanger is TRUE. Summary: Choice A is correct because it accurately describes the mechanism by which digoxin increases intracellular calcium levels. Choices B, C, and D are incorrect as they do not accurately represent the relationship between digoxin and intracellular calcium levels.