Diseases that reduce pancreatic enzyme secretions do NOT usually decrease the digestion and absorption of:

Correct Answer: D

Rationale: The correct answer is D: Sucrose. Diseases that reduce pancreatic enzyme secretions typically do not affect the digestion and absorption of sucrose because sucrose is primarily broken down in the small intestine by sucrase, an enzyme produced by the intestinal lining, not the pancreas. Animal proteins (choice A) and plant proteins (choice B) require pancreatic enzymes like trypsin and chymotrypsin for digestion; plant lipids (choice C) require pancreatic lipase for digestion. Therefore, choices A, B, and C would be affected by reduced pancreatic enzyme secretions, unlike sucrose.

Correct Answer: A

Rationale: The correct answer is A: upper gastrointestinal bleeding. Melena is black, tarry stool resulting from the digestion of blood in the gastrointestinal tract. This typically occurs in the upper GI tract due to the longer transit time, allowing the blood to be digested. Lower GI bleeding usually presents as bright red blood in the stool or maroon-colored stool. Therefore, melena is a specific indicator of upper GI bleeding. Choices B, C, and D are incorrect because melena specifically points to upper GI bleeding, not lower GI bleeding or both.

Correct Answer: B

Rationale: Certainly! The correct answer is B: Cholecystokinin (CCK) stimulates the contraction of the gallbladder. This hormone is released from the duodenum in response to the presence of fats and proteins in the small intestine. Its main function is to signal the gallbladder to contract and release bile into the duodenum to aid in the digestion and absorption of fats. A: CCK is not secreted from the jejunum but from the duodenum. C: CCK does not inhibit stomach motility; instead, it enhances the release of digestive enzymes and bile. In summary, choice B is correct as it accurately reflects the role of CCK in stimulating gallbladder contraction, while choices A and C are incorrect based on the functions of CCK in the digestive system.

Correct Answer: C

Rationale: The correct answer is C because saliva does not help in dental caries by increasing acidity; in fact, saliva helps neutralize acids and remineralize teeth. A: Saliva does help in articulation by lubricating the mouth. B: Saliva helps in swallowing by moistening food. D: Saliva contains lysozymes that kill microorganisms, aiding in oral hygiene.

Correct Answer: B

Rationale: The correct answer is B: Serosa. The serosa is the outermost layer of an organ lying within a body cavity. It is composed of connective tissue covered by a layer of mesothelium. This layer is farthest away from the inner core or lumen of the organ. The muscularis externa (choice A) is the layer of muscle tissue located just beneath the serosa. The mucosa (choice C) is the innermost layer of the organ, lining the lumen. The myenteric plexus (choice D) is a network of nerve fibers located between the circular and longitudinal layers of the muscularis externa, playing a role in regulating gastrointestinal motility.