Which of these statements about reflexes in the GI tract is false?

Correct Answer: C

Rationale: The correct answer is C because food that distends the stomach actually initiates short reflexes, not long reflexes. Short reflexes are provoked by nerves near the GI tract, which aligns with choice A. Short reflexes are indeed mediated by the enteric nervous system, supporting choice B. Long reflexes, as per choice D, can be provoked by stimuli originating outside the GI tract. Therefore, choice C is false as food distending the stomach triggers short reflexes, not long reflexes.

Correct Answer: D

Rationale: Step 1: Bile is produced in the liver, not the gallbladder. Step 2: Bile salts aid in digestion by emulsifying fats. Step 3: Bile salts are recycled in the enterohepatic circulation. Step 4: This recycling process conserves bile salts. Step 5: Choice D is correct as it accurately states that bile salts are recycled, supporting efficient digestion and absorption.

Correct Answer: B

Rationale: The correct answer is B: small intestine. The absorption of most nutrients occurs in the small intestine due to its large surface area, which is facilitated by villi and microvilli. Digestive enzymes and bile produced by the liver and pancreas help break down food into absorbable nutrients. Nutrients like carbohydrates, proteins, fats, vitamins, and minerals are absorbed through the walls of the small intestine and into the bloodstream for distribution to the body. The stomach primarily functions in digestion, while the large intestine absorbs water and salts and the rectum stores waste before elimination.

Correct Answer: B

Rationale: The correct answer is B: small intestine. Digestive enzymes are activated in the small intestine to break down nutrients. Firstly, enzymes are secreted by the pancreas into the small intestine, where they act on carbohydrates, proteins, and fats. Secondly, bile from the liver helps in the digestion of fats. The stomach mainly secretes gastric juices for protein digestion, not enzymes for overall digestion. The liver produces bile, not digestive enzymes. The pancreas secretes various digestive enzymes, but they become activated in the small intestine.

Correct Answer: A

Rationale: The correct answer is A: Parietal cells. Parietal cells secrete hydrochloric acid in the stomach to create the acidic environment necessary for digestion. They also secrete intrinsic factor for vitamin B12 absorption. Chief cells produce pepsinogen, not hydrochloric acid. Mucous neck cells secrete mucus to protect the stomach lining. Enteroendocrine cells secrete hormones like gastrin, not hydrochloric acid. Therefore, the correct choice is A as it directly produces hydrochloric acid in the stomach.