The small intestine contains fingerlike projections called ______, whose function is to ______.

Correct Answer: D

Rationale: The correct answer is D because villi are fingerlike projections in the small intestine that increase the surface area for nutrient absorption. Villi have microvilli on their surface, further increasing the absorption area. Option A is incorrect because villi do not secrete mucus; goblet cells in the intestine do. Option B is incorrect because rugae are folds in the stomach lining, not in the small intestine. Option C is incorrect because Crypts of Lieberkuhn are intestinal glands that produce substances, but they are not fingerlike projections like villi.

Correct Answer: C

Rationale: The correct answer is C: pancreas. The pancreas is the main source of lipase production in the body. Lipase is an enzyme responsible for breaking down fats into fatty acids and glycerol. The pancreas secretes pancreatic lipase into the small intestine where it aids in the digestion of fats. Salivary glands produce amylase for carbohydrate digestion, the stomach produces gastric lipase for limited fat digestion, and the small intestine produces additional digestive enzymes but not the majority of lipase.

Correct Answer: C

Rationale: Rationale for Correct Answer C: Enteropeptidase converts trypsinogen to trypsin by cleaving a peptide sequence that blocks the active site of trypsin. This is crucial for the activation of trypsin, a key enzyme in protein digestion. Trypsin then activates other pancreatic enzymes. This process ensures efficient breakdown of proteins in the small intestine. Summary of Incorrect Choices: A: Pepsinogen is not secreted by the pancreas and does not require removal of a peptide sequence from the active site for activation. B: Pancreatic α-amylase is responsible for breaking down starch into maltose and not glucose. D: Pancreatic secretion of hydrochloric acid is not directly related to the activation of pancreatic enzymes; it is the role of stomach acid to provide an acidic environment for pepsin activation.

Correct Answer: C

Rationale: The correct answer is C because the formation of tripartite synapses with astrocytes and neurons does not provide direct protection to the brain. Tripartite synapses involve communication between neurons and astrocytes, primarily for synaptic regulation and plasticity. The blood-brain barrier (A) physically protects the brain by restricting the passage of harmful substances. Microglia (B) function as the brain's immune cells, defending against pathogens and removing cellular debris. Therefore, choices A and B contribute to the brain's protection, making them incorrect answers.

Correct Answer: A

Rationale: Rationale: A is false because exercise has been shown to be as effective as, or even more effective than, metformin in slowing the progression of type 2 diabetes. Exercise helps improve insulin sensitivity and manage blood glucose levels, which are crucial for diabetes management. Choices B and C are true statements supported by scientific evidence. Choice D is incorrect as A is false, making the statement "none of the above are false" inaccurate.