Which of these is a characteristic of the small intestine?

Correct Answer: B

Rationale: The correct answer is B because the small intestine is where the majority of digestion occurs, including the breakdown of proteins, carbohydrates, and fats. This is facilitated by enzymes and bile produced by other organs. Villi in the small intestine increase surface area for absorption, making choice A incorrect. Absorption of water primarily occurs in the large intestine, so choice C is incorrect. Bile is produced by the liver and stored in the gallbladder, not the small intestine, making choice D incorrect. Thus, the small intestine's role in digestion makes it the correct characteristic.

Correct Answer: D

Rationale: The correct answer is D: Enteropeptidase. Enteropeptidase is not produced by the exocrine pancreas; it is produced by the duodenal mucosa. Proelastase, DNase, and amylase are enzymes produced by the exocrine pancreas. Proelastase is involved in the breakdown of elastin, DNase breaks down DNA, and amylase helps in the digestion of carbohydrates. Therefore, the correct answer is D because Enteropeptidase is not produced by the exocrine pancreas but by the duodenal mucosa.

Correct Answer: C

Rationale: The correct answer is C: Bile salts. Bile salts play a crucial role in the contraction of the gallbladder. When bile salts are released into the duodenum, they stimulate the gallbladder to contract, releasing bile into the small intestine to aid in digestion. Secretin (choice A) and VIP (choice B) are hormones that primarily regulate pancreatic secretion, not gallbladder contraction. Atropine (choice D) is an anticholinergic drug that inhibits the parasympathetic nervous system and would not stimulate gallbladder contraction. Therefore, the correct answer is C as bile salts directly trigger the contraction of the gallbladder.

Correct Answer: D

Rationale: The correct answer is D: Bile salts. Bile salts are primarily absorbed in the terminal ileum, not in the duodenum or jejunum. The duodenum and jejunum are mainly responsible for absorbing nutrients like glucose, fat-soluble vitamins, and vitamin C. Bile salts aid in the digestion and absorption of fats, but they are reabsorbed in the ileum to be recycled. Therefore, the duodenum and jejunum are not the main sites for the absorption of bile salts.

Correct Answer: C

Rationale: The correct answer is C: peptic ulcer. Peptic ulcers are a common cause of upper gastrointestinal hemorrhage due to erosion of the stomach lining. The acidic environment in the stomach can lead to ulcer formation. Esophageal varices are associated with liver cirrhosis, not a common cause of hemorrhage. Gastric carcinoma may cause bleeding but is less common than peptic ulcers. Gastritis is inflammation of the stomach lining and can cause bleeding but is not as common as peptic ulcers.