Which of these statements about the small intestine is true?

Correct Answer: B

Rationale: The correct answer is B. The small intestine is where the majority of digestion and absorption occur due to its large surface area for nutrient absorption. This is facilitated by villi and microvilli. Choice A is incorrect as the small intestine is lined with villi and microvilli, not smooth muscle. Choice C is incorrect because bile is produced in the liver and stored in the gallbladder. Choice D is incorrect as carbohydrate digestion primarily occurs in the mouth and small intestine.

Correct Answer: D

Rationale: Saliva does not contain platelets because platelets are components of blood responsible for blood clotting, not found in saliva. Saliva does contain ABO blood group antigens, lysozymes for antibacterial activity, and immunoglobulins for immune function. Platelets are not a normal component of saliva, making option D the correct answer.

Correct Answer: A

Rationale: After a cholecystectomy, the gallbladder is removed, affecting bile storage and release. The liver still produces bile, but it is not stored in the gallbladder for efficient release when needed. This results in inadequate bile availability to emulsify fats, leading to difficulty digesting fat-rich foods. Choices B and C are incorrect as they do not directly address the issue of insufficient bile production. Choice D is incorrect as bile concentration is not the primary concern post-cholecystectomy.

Correct Answer: D

Rationale: The correct answer is D because the oesophageal phase of swallowing starts when a bolus enters the oropharynx. This triggers the swallowing reflex, leading to the contraction of the upper oesophageal sphincter and relaxation of the lower sphincter to allow the bolus to move into the oesophagus. Choices A and B are incorrect because the oesophageal phase can proceed with the mouth open and is not primarily reflex-controlled by the myenteric plexus. Choice C is incorrect as the swallowing center in the brain coordinates and initiates the swallowing reflex but is not the primary control of the oesophageal phase.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Hematemesis refers to vomiting blood, which typically originates from the upper gastrointestinal tract. 2. Blood from the lower gastrointestinal tract is usually passed through the rectum as melena or hematochezia. 3. Therefore, hematemesis is a clear indication of upper gastrointestinal bleeding. 4. Choice A is correct because hematemesis specifically points to upper GI bleeding. Summary: - Choice B is incorrect because lower GI bleeding does not typically present with vomiting blood. - Choice C is incorrect as hematemesis is specific to upper GI bleeding. - Choice D is incorrect as hematemesis indicates an issue in the upper GI tract.