What is the function of the enteric nervous system?

Correct Answer: C

Rationale: The correct answer is C because the enteric nervous system is a complex network of neurons that controls digestion independently of the brain. It regulates gastrointestinal functions such as peristalsis, secretion of digestive enzymes, and blood flow. This system can operate autonomously but is also influenced by the central nervous system. Choices A, B, and D are incorrect because the enteric nervous system is not responsible for controlling voluntary movements, regulating hormone secretion, or controlling respiratory functions.

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.

Correct Answer: B

Rationale: The correct answer is B because the small intestine is primarily responsible for absorbing nutrients from digested food. It has specialized structures like villi to maximize nutrient absorption. Choice A is incorrect as the pancreas and other organs produce digestive enzymes. Choice C is incorrect as the liver produces bile. Choice D is incorrect as waste is stored in the large intestine, not the small intestine.