What is the function of the villi in the small intestine?

Correct Answer: B

Rationale: The function of the villi in the small intestine is to absorb nutrients. Villi increase surface area for absorption. They contain blood vessels and lacteals that absorb digested nutrients. Villi do not produce digestive enzymes (A), bile (C), or store glycogen (D). Digestive enzymes are produced by the pancreas and bile by the liver. Glycogen is stored in the liver and muscles.

Correct Answer: D

Rationale: The correct answer is D because micelles are indeed clusters of cholesterol, fatty acids, bile salts, and 2 mono-glycerides formed in the small intestine during lipid digestion. This process aids in the absorption of lipids by increasing their surface area for enzymatic action. Choice A is incorrect as emulsified fat globules are not micelles, but rather the initial step in lipid digestion. Choice B is incorrect as pro-enzymes are not related to micelles. Choice C is incorrect as dead enterocytes are not involved in micelle formation.

Correct Answer: D

Rationale: The correct answer is D because iron absorption is regulated to meet the body's needs. When body stores are low or erythropoiesis is increased, absorption increases. This process occurs mainly in the duodenum and upper jejunum, not the terminal ileum as stated in option C. Option A is incorrect because HCl aids in converting iron into a more absorbable form but does not determine the percentage absorbed. Option B is incorrect as the majority of iron absorption occurs in the duodenum and upper jejunum, not the small intestine in general.

Correct Answer: A

Rationale: The correct answer is A: resecting the constricted segment. In Hirschsprung's disease, there is a lack of ganglion cells in the distal bowel causing a functional obstruction. The treatment involves surgically removing the affected segment to allow normal bowel function. Resecting the dilated segment (choice B) is not effective as the issue lies in the constricted area. Colectomy and ileostomy (choice C) is an extreme measure and is usually reserved for severe cases. Avoiding surgical intervention (choice D) is not recommended as it can lead to complications and worsen the condition.

Correct Answer: B

Rationale: B: Carcinoma of the esophagus is difficult to cure due to local spread. Esophageal cancer often presents at advanced stages, making complete surgical resection challenging. Local spread to nearby structures like the trachea or blood vessels hinders curative treatment. This is supported by the fact that esophageal cancer has a poor prognosis, with a 5-year survival rate of around 20%. A: This is incorrect because esophageal carcinoma is often diagnosed at advanced stages when symptoms appear, making it less curable than early-stage cancers. C: Early widespread metastases are not a defining feature of esophageal carcinoma. Metastases typically occur at later stages of the disease. D: Esophageal carcinoma can be differentiated or undifferentiated, but this does not impact the difficulty in curing the cancer due to local spread.