Which of the following is correct regarding the cells of the gastric pit?

Correct Answer: D

Rationale: The correct answer is D because G cells in the gastric pit secrete gastrin, not histamine. Gastrin stimulates the release of hydrochloric acid in the stomach. Mucous cells are not enteroendocrine, so A is incorrect. G cells are not exocrine, making B incorrect. D cells secrete somatostatin, not histamine, so C is also incorrect.

Correct Answer: A

Rationale: The correct answer is A. Mass peristalsis refers to the coordinated contraction of the smooth muscle in the colon that helps move fecal matter towards the rectum. This process specifically occurs in the large intestine, not the small intestine. Therefore, choice A is incorrect. Choice B is incorrect because mass peristalsis is actually a rapid and powerful movement, not slow. Choice C is correct as it accurately describes the role of mass peristalsis in facilitating the movement of fecal matter in the large intestine. Choice D is incorrect because choice A is incorrect.

Correct Answer: B

Rationale: The correct answer is B because swallowing is controlled by the swallowing center in the medulla oblongata. This center coordinates the complex sequence of muscle contractions involved in swallowing, ensuring food moves from the mouth to the esophagus without entering the airway. The pharyngeal phase is actually involuntary, not voluntary (Choice A). Swallowing usually occurs with a closed mouth, not an open one (Choice C). Additionally, the buccal phase is not accompanied by apnea; breathing typically continues during this phase (Choice D). Therefore, the correct answer is B due to the central control of swallowing in the medulla oblongata.

Correct Answer: A

Rationale: The correct answer is A: Emulsify fats. Bile emulsifies fats by breaking them down into smaller droplets, increasing the surface area for enzymes to work on, aiding in the digestion and absorption of fats. Choices B and C are incorrect as bile specifically targets fats, not proteins or carbohydrates. Choice D is incorrect as bile plays a crucial role in fat digestion.

Correct Answer: B

Rationale: The correct answer is B: stomach. Chemical digestion of protein begins in the stomach where the enzyme pepsin breaks down proteins into peptides. The stomach's acidic environment activates pepsinogen to pepsin. In contrast, the mouth primarily performs mechanical digestion through chewing, and the small intestine is where further breakdown and absorption of nutrients occur. The large intestine mainly absorbs water and electrolytes, with minimal involvement in protein digestion.