What is the role of the large intestine?

Correct Answer: C

Rationale: The large intestine's main role is to absorb water from the indigestible food residue, forming feces. This process helps maintain proper hydration levels in the body. It does not digest proteins (choice A) or absorb nutrients (choice B), as these processes primarily occur in the small intestine. The production of bile (choice D) is carried out by the liver and stored in the gallbladder, not by the large intestine. Thus, choice C is correct as it aligns with the primary function of the large intestine.

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: B

Rationale: The correct answer is B: Diseases of the inner ear. Vomiting is primarily controlled by the vomiting center in the brainstem, which responds to various stimuli such as irritation of the duodenal mucosa (Choice A), microbial toxins in the blood (Choice C), and severe exercise (Choice D). Diseases of the inner ear do not directly trigger the vomiting reflex, making Choice B the correct answer.

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.