Which cells in the small intestine may help protect the intestinal epithelium from bacteria?

Correct Answer: C

Rationale: Granular cells, also known as Paneth cells, produce antimicrobial peptides to protect the intestinal epithelium from bacteria. These peptides have antimicrobial properties that help prevent bacterial overgrowth and maintain intestinal homeostasis. Absorptive cells are primarily responsible for nutrient absorption, while goblet cells secrete mucus for lubrication. Endocrine cells produce hormones that regulate various physiological processes. Therefore, the correct answer is C, as granular cells play a direct role in protecting the intestinal epithelium from bacteria.

Correct Answer: D

Rationale: The correct answer is D: high-density lipoprotein (HDL). HDL is known to have a higher proportion of protein compared to other lipoproteins. In this case, with 45% protein content, it aligns with the typical composition of HDL. HDL is responsible for transporting cholesterol from peripheral tissues back to the liver for excretion, making it crucial for maintaining cardiovascular health. A: Micelle is incorrect as it is a single-layered structure formed by amphipathic molecules in a specific environment like bile salts in the intestines. B: Chylomicron is incorrect as it is primarily composed of triglycerides and is responsible for transporting dietary lipids. C: Low-density lipoprotein (LDL) is incorrect as it typically has higher cholesterol content compared to HDL and is known as "bad cholesterol" due to its role in depositing cholesterol in arteries.

Correct Answer: A

Rationale: The correct answer is A because the absorption of vitamins from the intestine involves various mechanisms. Vitamin E is indeed absorbed by a protein that binds peroxidized fatty acids. Thiamine pyrophosphate and pyridoxal phosphate need to be dephosphorylated before absorption. Oxidized vitamin C is absorbed by a glucose transporter. Therefore, all the options given are correct as they describe different aspects of the absorption process. Each choice provides a unique insight into how different vitamins are absorbed, highlighting the complexity of the absorption process.

Correct Answer: C

Rationale: The correct answer is C because macrophages can indeed infiltrate enlarged adipocytes in obesity. This is a true statement as obesity is associated with chronic low-grade inflammation in adipose tissue, leading to macrophage infiltration. Option A is incorrect as inflammation can also occur in response to tissue damage. Option B is incorrect as inflammation is a normal and necessary response to injury or infection for tissue repair. Option D is incorrect as statement C is true.

Correct Answer: C

Rationale: The correct answer is C because an increase in oxygen does not contribute to local vasodilation during muscle contraction. Oxygen is typically consumed by working muscles and does not act as a vasodilator. On the other hand, increases in carbon dioxide and hydrogen ions lead to vasodilation by stimulating the release of vasodilatory substances. Choice D is incorrect because oxygen, in this context, does not contribute to vasodilation like carbon dioxide and hydrogen ions do.