Which of these is responsible for the formation of chyme?

Correct Answer: C

Rationale: The correct answer is C: hydrochloric acid. Hydrochloric acid is responsible for creating an acidic environment in the stomach essential for the activation of pepsin and the breakdown of proteins into peptides. This acidic environment also helps in the denaturation of proteins and kills harmful bacteria present in food. Bile (choice A) aids in digestion of fats in the small intestine. Mucus (choice B) helps protect the stomach lining from the acidic environment. Pepsin (choice D) is an enzyme that breaks down proteins but is activated by hydrochloric acid.

Correct Answer: B

Rationale: The colon's main role in digestion is the absorption of water and electrolytes from undigested food, forming feces. This process helps maintain body fluid balance. The other choices are incorrect because: A) Carbohydrates are primarily digested in the small intestine. C) Bile is produced in the liver and stored in the gallbladder, aiding in fat digestion in the small intestine. D) Enzymes are secreted in the stomach and small intestine to aid in digestion, not in the colon.

Correct Answer: B

Rationale: The correct answer is B: Large intestine. The large intestine is responsible for the absorption of water and electrolytes from the remaining indigestible food matter that passes through the small intestine. It reabsorbs water and electrolytes to maintain the body's fluid balance. The small intestine primarily absorbs nutrients and vitamins, while the stomach is responsible for the initial digestion of food and the pancreas secretes digestive enzymes into the small intestine. Therefore, the large intestine is the correct choice for water and electrolyte absorption in the digestive system.

Correct Answer: D

Rationale: The correct answer is D because an inhibitor of the hydrogen-potassium pump directly targets the mechanism responsible for the secretion of hydrochloric acid in the stomach. By inhibiting this pump, the production of acid is reduced. A H receptor blocker (choice A) and a muscarinic cholinergic receptor blocker (choice C) work by blocking specific receptors involved in stimulating acid secretion. A nicotinic cholinergic receptor blocker (choice B) blocks a different type of receptor that is not directly involved in regulating acid secretion. In summary, the inhibitor of the hydrogen-potassium pump (choice D) is the most direct and effective way to reduce the secretion of hydrochloric acid in the stomach compared to the other choices.

Correct Answer: B

Rationale: The correct answer is B because the submandibular salivary gland is responsible for producing around 70-75% of total saliva, including amylase. If it stops functioning, there would be a severe deficiency of amylase, leading to impaired digestion of starches. Choice A is incorrect because the reduction in salivary secretion would be more significant than 20%. Choice D is incorrect as mucins are produced by other salivary glands and not solely by the submandibular gland.