During a long-distance run on a hot day, an athlete produces large quantities of sweat. As a result, the kidneys change the rate of urine production. Why is this change important?

Correct Answer: C

Rationale: The correct answer is C: Decreased urine production allows the body to conserve water. When an athlete sweats a lot during a long-distance run on a hot day, the body loses water through sweat. To prevent dehydration, the kidneys reduce urine production, allowing the body to retain more water. This helps maintain proper hydration levels and prevent water loss. Rationale: A: Decreased urine production does not directly impact amino acids in the blood. Amino acids are primarily regulated by protein metabolism and dietary intake. B: Increased urine production does not specifically target the removal of amino acids produced during exercise. Amino acids are typically metabolized and used for energy or protein synthesis. D: Increased urine production does not help more water remain in the bloodstream. Excess water is typically excreted to maintain fluid balance.

Correct Answer: A

Rationale: The correct answer is A: Duodenal ulcer. The patient's symptoms of pain relieved by food intake and waking up at night with stomach pain are classic signs of a duodenal ulcer. The pain is alleviated by neutralizing gastric acid with food and worsens when the stomach is empty. Gastric ulcers typically worsen with food intake and are associated with weight loss. Esophageal ulcers present with difficulty swallowing and chest pain. Refractory ulcers are those that do not heal despite treatment. Therefore, based on the patient's symptoms, a duodenal ulcer is the most likely diagnosis.

Correct Answer: C

Rationale: The correct answer is C: Proton pump inhibitors (PPIs). PPIs are commonly used to reduce stomach acid in the treatment of peptic ulcer disease by inhibiting the proton pump in the gastric parietal cells. This reduces the production of stomach acid, allowing the ulcer to heal. Aspirin and ibuprofen can actually worsen peptic ulcers by irritating the stomach lining. Acetaminophen is not used to reduce stomach acid and does not directly treat peptic ulcers.

Correct Answer: D

Rationale: The correct answer is D because every mucosa consists of a surface epithelial layer, with or without glands, along with an underlying layer of loose connective tissue. This structure allows for protection, secretion, and absorption functions of mucosal surfaces. A simple epithelium (choice A) and a stratified epithelium (choice B) alone do not adequately support these functions. Choice C is incorrect because not all mucosas have associated glands, and the presence of loose connective tissue is crucial for proper mucosal function.

Correct Answer: B

Rationale: The correct answer is B because the submucosa of the GI tract typically contains the nerves and parasympathetic ganglia of the submucosal (Meissner's) plexus. This plexus regulates gastrointestinal secretion and blood flow. Choice A is incorrect because smooth muscle layers are found in the muscularis externa, not the submucosa. Choice C is incorrect as the myenteric plexus is located between the circular and longitudinal muscle layers of the muscularis externa. Choice D is incorrect because the submucosa contains a rich network of blood vessels for nutrient absorption and immune function.