Histamine stimulates the ______ cells to release ______.

Correct Answer: C

Rationale: Histamine stimulates the parietal cells in the stomach lining to release hydrochloric acid (HCl). This process plays a crucial role in the digestion of food. Parietal cells are responsible for producing stomach acid, which helps break down food and kill bacteria. Choice A is incorrect because intrinsic factor is not released by parietal cells in response to histamine. Choice B is incorrect because pepsinogen is released by chief cells, not parietal cells. Choice D is incorrect because mucous neck cells secrete mucus to protect the stomach lining, but they are not directly stimulated by histamine to release mucus.

Correct Answer: A

Rationale: The correct answer is A: mass movements. Mass movements are strong contractions that occur 3 to 4 times a day, moving large amounts of fecal material through the colon. This process involves the transverse and descending colon, which aligns with the description provided in the question. Mass movements help propel waste towards the rectum for elimination. Choice B, haustral churning, refers to the mixing and propelling actions that occur in the haustra of the colon, not involving large parts of the transverse and descending colon. Choice C, the defecation reflex, is the process that triggers the urge to defecate, not specific contractions involving the colon. Choice D, teniae coli waves, are contractions of the longitudinal muscles of the colon that create the haustra, not the strong propulsive contractions described in the question.

Correct Answer: D

Rationale: Rationale for Correct Answer D (Triglycerides must be emulsified and digested before fatty acids can be transported): 1. Triglycerides are large molecules that cannot be directly absorbed by the intestinal cells. 2. Emulsification breaks down triglycerides into smaller droplets, increasing the surface area for enzyme action. 3. Enzymatic digestion of triglycerides by lipases results in the release of fatty acids and monoglycerides. 4. These breakdown products are then absorbed by enterocytes in the small intestine. Summary of Why Other Choices are Incorrect: A: FABP and FAT/CD36 proteins are involved in fatty acid transport, not triglyceride digestion. B: Both medium and long-chain triglycerides are absorbed into the lymphatic system via chylomicrons. C: While mixed micelles aid in lipid absorption, they are not essential for the initial digestion of triglycerides.

Correct Answer: A

Rationale: The correct answer is A: regurgitation of the food into the oesophagus. The cardiac sphincter is located at the junction between the esophagus and the stomach. Its main function is to prevent the backflow of stomach contents into the esophagus. If the cardiac sphincter fails to function properly, it can lead to regurgitation, where stomach contents flow back into the esophagus, causing discomfort and potential damage to the esophageal lining. Summary: B: Loss of control of defecation is not related to the cardiac sphincter, as it primarily functions in the upper digestive tract. C: Movement of the bolus into the trachea is related to swallowing reflex and epiglottis function, not the cardiac sphincter. D: Rapid emptying from the stomach to the small intestine is controlled by the pyloric sphincter, not the cardiac sphincter.

Correct Answer: A

Rationale: The correct answer is A: it is converted into fat. Excess glucose not needed for immediate energy or stored as glycogen is converted into fat through a process called de novo lipogenesis in the liver. This occurs when glucose levels are high and glycogen stores are full. The liver converts the excess glucose into fatty acids and then into triglycerides for storage in adipose tissue. This process helps regulate blood glucose levels and prevents hyperglycemia. Other choices are incorrect: B: Glucose is not directly converted into protein. Proteins are synthesized from amino acids, not glucose. C: Releasing excess glucose back into the bloodstream would lead to high blood sugar levels, which is not a typical physiological response. D: Glucose is not simply degraded; it is either used for energy, stored as glycogen, or converted into fat when in excess.