Which one of the following does not occur during swallowing?

Correct Answer: C

Rationale: The correct answer is C because the uvula and soft palate actually move superiorly, not inferiorly, during swallowing to close off the nasopharynx and prevent food or liquid from entering the nasal cavity. A) The larynx raises to prevent food from entering the trachea. B) The epiglottis moves anteriorly to cover the glottis and prevent aspiration. D) The vestibular folds move laterally to help seal off the airway during swallowing.

Correct Answer: C

Rationale: Rationale: The correct answer is C: urea. Ammonia is toxic and needs to be converted into a less toxic form for excretion. The liver combines ammonia with carbon dioxide to form urea through the urea cycle. Urea is water-soluble and is excreted by the kidneys in urine. Cholesterol (A) is a lipid molecule, bilirubin (B) is a by-product of heme metabolism, and uric acid (D) is a by-product of purine metabolism. These molecules are not formed from the combination of ammonia and carbon dioxide and are not excreted in the kidneys.

Correct Answer: A

Rationale: The correct answer is A: lactose intolerance. This is due to the inability to digest lactose, the sugar found in dairy products, leading to symptoms like intestinal cramps, bloating, and diarrhea. This is a common condition caused by a deficiency of lactase enzyme. Choice B: Diabetes mellitus, Type I, is incorrect as it is an autoimmune condition affecting insulin production, not digestion of dairy products. Choice C: Heartburn is incorrect as it is a symptom of acid reflux, not related to dairy product intolerance. Choice D: Peritonitis is incorrect as it is an inflammation of the abdominal lining, usually caused by infection or injury, not related to dairy product intolerance.

Correct Answer: D

Rationale: The correct answer is D because the presence of folds, villi, and microvilli on the surface of enterocytes significantly increases the absorptive area of the intestine. The folds increase the surface area, villi further increase the surface area, and microvilli further amplify the absorptive surface. This intricate structure allows for efficient absorption of nutrients. Option A is incorrect as the absorptive area is not equivalent to a tennis court. Option B is incorrect because not all options are correct. Option C is incorrect because changes in motility can affect nutrient absorption but do not directly relate to the absorptive area of the intestine like the structural features mentioned in option D.

Correct Answer: B

Rationale: Rationale: Choice B is correct because GABA is indeed released by GABA neurons and acts to inhibit the propagation of signals triggered by dopamine in the post-synaptic neuron. GABA functions as an inhibitory neurotransmitter in the central nervous system. Choices A and C are incorrect. Choice A is inaccurate because GABA inhibits the release of dopamine, not the other way around. Choice C is incorrect as heroin and morphine act on opioid receptors, not GABA receptors. Choice D is incorrect because not all statements are true.