The fauces refer to the

Correct Answer: A

Rationale: The correct answer is A: opening into the oropharynx. The fauces are the opening at the back of the mouth that leads into the oropharynx, connecting the mouth to the throat. This is where food and liquid pass through when swallowing. Choices B, C, and D are incorrect because the fauces specifically refer to the opening into the oropharynx, not the space between the cheek and gums, the cavity containing the tongue and teeth, or the opening into the larynx.

Correct Answer: C

Rationale: The correct answer is C because duodenal cells release secretin in response to low pH in chyme. Secretin inhibits gastric secretions by stimulating the pancreas to release bicarbonate-rich fluid to neutralize the acidic chyme. Option A is incorrect because gastric inhibitory polypeptide and cholecystokinin actually stimulate pancreatic secretion, not inhibit gastric secretions. Option B is incorrect as the enterogastric reflex decreases gastric secretions to slow down the rate of emptying the stomach, not increase it. Option D is incorrect because enterogastrone is a hypothetical hormone and not involved in the regulation of gastric secretions.

Correct Answer: B

Rationale: The correct answer is B: cholecystokinin; low pH of the chyme. Cholecystokinin is released in response to the presence of fats and proteins in the duodenum. This hormone stimulates the gallbladder to release bile into the small intestine to aid in the digestion and absorption of fats. The low pH of the chyme triggers the release of cholecystokinin as it indicates the presence of undigested fats and proteins, signaling the need for more bile to aid in their digestion. Choices A, C, and D are incorrect because cholecystokinin is specifically released in response to the low pH of the chyme, not the high pH. Secretin, on the other hand, is released in response to the high pH of the chyme to stimulate bicarbonate release from the pancreas to neutralize the acidic chyme, not for bile secretion.

Correct Answer: D

Rationale: The correct answer is D: amylase. Amylase is the enzyme responsible for breaking down starch into maltose. It works by catalyzing the hydrolysis of the glycosidic bonds between glucose molecules in starch. Lipase (A) breaks down lipids, not carbohydrates. Maltase (B) is responsible for breaking down maltose into glucose. Lactase (C) breaks down lactose, not starch. Therefore, amylase is the correct enzyme for breaking down starch into maltose.

Correct Answer: C

Rationale: The correct answer is C because hemicelluloses, pectins, and inulin are indeed rapidly fermented to short-chain fatty acids in the colon, providing trophic effects. This is supported by scientific evidence. Choice A is incorrect because the main end products of fermentation of dietary fiber are short-chain fatty acids, not malic, succinic, and propionic acids. Choice B is incorrect as not all forms of fiber are completely fermented within 24 hours, and the time frame can vary. Choice D is incorrect because stool bulking is primarily attributed to soluble fibers, which hold water and increase stool bulk, rather than insoluble fibers like cellulose.