Cells which secrete pepsinogen into the stomach are called:

Correct Answer: B

Rationale: The correct answer is B: chief (zymogenic) cells. These cells are responsible for secreting pepsinogen, which is the inactive form of pepsin, an enzyme that helps in the digestion of proteins in the stomach. Goblet cells (A) secrete mucus, parietal (oxyntic) cells (C) secrete hydrochloric acid, and Kupffer cells (D) are found in the liver and are involved in immune function, not in stomach digestion. Therefore, the correct choice is chief (zymogenic) cells as they specifically secrete pepsinogen for protein digestion in the stomach.

Correct Answer: D

Rationale: Absorptive epithelial cells of the small intestine (enterocytes) are characterized by: A: Apical brush border composed of microvilli - This increases surface area for absorption. B: A glycocalyx containing various digestive enzymes - This aids in digestion and absorption. C: Junctional complexes including tight junctions separating apical from lateral cell membranes - This maintains cell polarity and regulates permeability. Therefore, choice D is correct as all these characteristics are typical of absorptive epithelial cells in the small intestine.

Correct Answer: B

Rationale: The correct answer is B: central vein. The hepatic lobule is a structural unit of the liver, consisting of hepatocytes arranged in a hexagonal pattern around a central vein. Hepatocytes receive oxygenated blood from the hepatic artery and nutrient-rich blood from the portal vein. These blood vessels merge within the lobule, and the blood flows towards the central vein. Bile produced by hepatocytes drains into bile canaliculi and eventually into bile ducts, which are not directly associated with defining the hepatic lobule. Therefore, the central vein is the correct answer as it is the vessel that receives blood from the sinusoids in the lobule.

Correct Answer: A

Rationale: The correct answer is A: hepatocytes. The term liver parenchyma refers to the functional cells of the liver responsible for its essential functions, such as metabolism, detoxification, and synthesis. Hepatocytes make up the majority of the liver's mass and are crucial for its normal functioning. Portal veins and hepatic arteries (choice B) are blood vessels supplying the liver, bile ducts (choice C) are responsible for transporting bile, and stored glycogen (choice D) is a form of stored energy in the liver, but they do not specifically refer to the liver parenchyma.

Correct Answer: D

Rationale: The correct answer is D: breakdown of hemoglobin. Hepatocytes do not breakdown hemoglobin; this function occurs primarily in the spleen. A: drug detoxification is correct as the liver metabolizes and detoxifies drugs. B: protein synthesis is also correct as hepatocytes produce various proteins. C: gluconeogenesis is correct as the liver can synthesize glucose from non-carbohydrate sources. Therefore, the breakdown of hemoglobin is the only function not performed by hepatocytes.