What is the role of the stomach in digestion?

Correct Answer: B

Rationale: The correct answer is B: Chemical digestion of proteins. The stomach produces hydrochloric acid and enzymes like pepsin to break down proteins into peptides and amino acids. This process is essential for protein digestion. Mechanical digestion (A) occurs mainly in the mouth and intestines. Absorption of nutrients (C) primarily takes place in the small intestine. Neutralization of stomach acid (D) is not the primary role of the stomach; rather, the stomach maintains an acidic environment for digestion.

Correct Answer: D

Rationale: The correct answer is D: Absorption of sodium. Colonic mucosal cells are efficient in absorbing sodium through active transport processes. Sodium absorption helps in maintaining fluid and electrolyte balance. Choices A, B, and C are incorrect because primary bile acids are converted into secondary bile acids in the liver, bilirubin is converted into stercobilinogen in the intestines, and aromatic amino acids are mostly absorbed in the small intestine, not the colon.

Correct Answer: B

Rationale: The migrating motor complex (MMC) functions to clear non-digestible material from the stomach and small intestine during fasting periods. Step 1: During fasting, MMC promotes gastrointestinal motility to prevent bacterial overgrowth. Step 2: MMC consists of 3 phases - quiescent, irregular contractions, and intense contractions - aiding in sweeping undigested materials. Step 3: This process helps maintain gut health and prevents issues like bacterial overgrowth or malabsorption. Summary: Choices A, C, and D are incorrect as they do not accurately describe the specific function of the migrating motor complex during fasting.

Correct Answer: C

Rationale: The correct answer is C: both. Occult fecal blood can indicate bleeding anywhere along the gastrointestinal tract. Upper gastrointestinal bleeding typically presents as melena (black, tarry stools), while lower gastrointestinal bleeding can manifest as occult blood in the stool. Therefore, occult fecal blood can be an indication of both upper and lower gastrointestinal bleeding. Choices A and B are incorrect because occult fecal blood is not exclusive to either upper or lower gastrointestinal bleeding alone. Choice D is incorrect since occult fecal blood can indeed be an indication of gastrointestinal bleeding.

Correct Answer: A

Rationale: The correct answer is A: Hemolytic jaundice is caused by more fragile RBCs. When red blood cells are destroyed at an increased rate, it leads to the release of more bilirubin, causing jaundice. Choice B is incorrect because liver damage leads to hepatocellular jaundice, not hemolytic. Choice C is incorrect as hemolytic jaundice is characterized by high bilirubin levels in the blood, not low levels in urine. Choice D is incorrect as option A is the correct explanation for hemolytic jaundice.