Which of the following is the primary function of the small intestine?

Correct Answer: C

Rationale: The correct answer is C: absorption of nutrients. The small intestine is responsible for absorbing nutrients from digested food into the bloodstream for distribution to the body's cells. It has specialized structures like villi and microvilli to maximize absorption surface area. Choice A is incorrect because while the small intestine does play a role in digesting fats, it is not its primary function. Choice B is incorrect because the digestion of carbohydrates primarily occurs in the mouth and stomach. Choice D is incorrect as the small intestine does not store bile, but rather receives it from the liver and gallbladder to aid in digestion.

Correct Answer: A

Rationale: The correct answer is A: It gives bile its color. Bilirubin is a pigment produced from the breakdown of hemoglobin in the liver, giving bile its characteristic yellow-green color. This is important for bile to aid in the emulsification and digestion of fats. Choices B and D are incorrect as stercobilinogen is produced from bilirubin in the intestine, contributing to stool color, not bile color. Choice C is incorrect as bile salts, not bilirubin, facilitate the absorption of lipids in the small intestine.

Correct Answer: D

Rationale: The correct answer is D because parasympathetic stimulation causes the contraction of the gall bladder. This is due to the release of acetylcholine which stimulates the gall bladder to contract and release bile into the duodenum to aid in digestion. Choices A, B, and C are incorrect as parasympathetic stimulation does not cause constriction of the pylorus, contraction of the internal anal sphincter, or contraction of the external anal sphincter.

Correct Answer: B

Rationale: The correct answer is B: congenital heterotopia. This is because the presence of small intestinal type epithelium in the gastric mucosa indicates ectopic tissue that is not normally found in the stomach. This condition is known as congenital heterotopia, where tissues from one organ are found in another due to developmental abnormalities. A: Chronic gastritis would not lead to the presence of small intestinal type epithelium in the gastric mucosa. C: Precancerous dysplasia refers to abnormal cellular changes that can progress to cancer but does not explain the presence of small intestinal type epithelium. D: Metastatic carcinoma would involve the spread of cancer cells from another primary site, not the presence of ectopic tissue.

Correct Answer: B

Rationale: Step-by-step rationale for why choice B is correct: 1. Carcinoid tumors can produce systemic symptoms due to the release of bioactive substances. 2. Metastasis to the liver can lead to the production of systemic symptoms like flushing and diarrhea. 3. This systemic symptom production is a characteristic feature of carcinoid tumors. 4. Choice B accurately describes the biologic nature of carcinoid tumors in relation to systemic symptoms. Summary of why other choices are incorrect: A: Carcinoid tumors can be malignant and produce systemic symptoms, so they are not always benign. C: Carcinoid tumors originating in the appendix are typically associated with a more favorable prognosis. D: Jejunal ulceration due to gastrin elaboration is more commonly seen in gastrinomas, not carcinoid tumors.