Secretory products of pancreatic β-cells are:

Correct Answer: B

Rationale: The correct answer is B because pancreatic β-cells secrete insulin, C-peptide, proinsulin, and islet amyloid polypeptide (IAPP). Insulin regulates blood sugar levels, C-peptide is a byproduct of insulin synthesis, proinsulin is the precursor of insulin, and IAPP helps in glucose metabolism. Choice A is incorrect as glucagon is secreted by α-cells, not β-cells, and proglucagon is not a primary secretory product of β-cells. Choice C is incorrect as somatostatin is mainly secreted by δ-cells in the pancreas, not β-cells. Choice D is incorrect as pancreatic polypeptide (PP) is secreted by PP-cells, a separate cell type in the pancreas, not by β-cells.

Correct Answer: A

Rationale: The correct answer is A, Piperidines like Loratadine and Fexofenadine are noted for their non-sedating effects due to their low penetration of the blood-brain barrier. This is because they have a low affinity for the central nervous system H1 receptors. In contrast, choices B, C, and D contain antihistamines that are known for their sedative effects due to their high penetration of the blood-brain barrier and high affinity for central nervous system H1 receptors. Therefore, Piperidines are the exception among the listed categories in not causing sedation.

Correct Answer: B

Rationale: The correct answer is B: Vitamin A. Vitamin A can be synthesized from a dietary precursor beta-carotene, which is found in various fruits and vegetables. The body converts beta-carotene into active Vitamin A as needed. Vitamin C (A) cannot be synthesized from a dietary precursor and must be obtained directly from the diet. Vitamin B1 (C) and Vitamin B6 (D) are water-soluble vitamins that cannot be synthesized from dietary precursors.

Correct Answer: A

Rationale: Rationale for Correct Answer (A): 1. A lipoprotein is a conjugated protein with a lipid component, facilitating lipid transportation in the blood. 2. Lipoproteins play a crucial role in transporting lipids such as cholesterol and triglycerides in the bloodstream. 3. They consist of proteins (apolipoproteins) and lipids, enabling solubility of lipids for transport. 4. Lipoproteins are classified based on density (e.g., HDL, LDL), reflecting their lipid and protein composition. Summary of Incorrect Choices: B: This describes vitamins, not lipoproteins. Vitamins are organic substances essential for bodily functions but are not lipoproteins. C: Endocrine gland secretions are hormones, not lipoproteins. Hormones regulate bodily functions and are not directly related to lipid transportation. D: Lipoproteins are not mediators of the inflammatory process. Inflammation involves immune responses, not lipid transport.

Correct Answer: C

Rationale: Step-by-step rationale for why Choice C: Gemfibrozil (Loprol) is correct: 1. Gemfibrozil is a fibric acid derivative known to increase HDL levels. 2. It works by activating lipoprotein lipase, which increases the breakdown of triglycerides and raises HDL levels. 3. Cholestyramine (A) is a bile acid sequestrant that does not affect HDL levels. 4. Lovastatin (B) is a statin that primarily lowers LDL levels. 5. Probucol (D) is an antioxidant that mainly lowers LDL levels and does not significantly impact HDL levels.