Where does the majority of chemical digestion in the stomach occur?

Correct Answer: A

Rationale: The majority of chemical digestion in the stomach occurs in the fundus and body regions. These areas contain gastric glands that secrete hydrochloric acid and pepsinogen, which break down proteins. The fundus and body also mix and churn food to create chyme. The cardia and pylorus do not play a significant role in chemical digestion. The cardia is the entry point of the stomach and mainly responsible for food entry, while the pylorus regulates the release of chyme into the small intestine. The body region alone does not have as many gastric glands compared to the fundus and is mainly involved in mixing and storing food.

Correct Answer: B

Rationale: The correct answer is B: liver. The liver is responsible for the production of bile, which is a greenish-yellow fluid that aids in digestion by emulsifying fats. Bile is stored and concentrated in the gallbladder (not produced by it). The pancreas produces digestive enzymes, not bile. The small intestine is where bile is released to help with the digestion of fats, but it is not responsible for its production. Therefore, the liver is the correct answer as it is the primary organ involved in bile production.

Correct Answer: B

Rationale: The correct answer is B: stomach. The stomach is responsible for mechanical digestion through the churning and mixing of food with gastric juices, breaking it down into smaller particles. The mouth initiates digestion by chewing and mixing food with saliva, but it primarily focuses on chemical digestion through enzymes. The small intestine is where most of the chemical digestion and nutrient absorption occur, not mechanical digestion. The large intestine's main function is water absorption and the formation of feces, not mechanical digestion. Therefore, the stomach is the correct choice for mechanical digestion in the digestive system.

Correct Answer: A

Rationale: The correct answer is A: parietal cells. Parietal cells are the specific type of cell in the stomach responsible for secreting hydrochloric acid. They play a crucial role in the digestion process by creating an acidic environment necessary for the activation of digestive enzymes and breakdown of food. Chief cells mainly produce pepsinogen, mucous cells secrete mucus for protection, and enteric cells are related to the enteric nervous system, not acid secretion in the stomach. Therefore, parietal cells are the correct choice for this question.

Correct Answer: C

Rationale: The correct answer is C: Liver. The liver produces bile, which plays a crucial role in digestion by breaking down fats. The pancreas (A) produces digestive enzymes, not bile. The gallbladder (B) stores bile produced by the liver but does not produce it. The stomach (D) produces gastric juices, not bile. Therefore, the liver is the only organ that produces bile, making it the correct answer.