Base your answer to the following question on the diagram below. A digestive function of organ C is the synthesis and secretion of

Answer Explanation

A) Mouth, Esophagus, Stomach: This option is incorrect because while saliva in the mouth does contain digestive enzymes (such as amylase for breaking down carbohydrates), the esophagus is not a site of enzyme secretion. The stomach secretes gastric juices which primarily contain hydrochloric acid and pepsinogen (which is converted to pepsin, a protein-digesting enzyme), but the esophagus itself does not secrete digestive enzymes.

B) Stomach, Small Intestine, Large Intestine: This option is incorrect because while both the small intestine and the large intestine play crucial roles in digestion and absorption, enzyme secretion mainly occurs in the stomach and small intestine. The large intestine primarily absorbs water and salts and does not secrete digestive enzymes.

C) Mouth, Stomach, Small Intestine: This option is correct. Enzymes are secreted in the mouth (amylase), stomach (pepsin for protein digestion), and small intestine (various enzymes including pancreatic enzymes like lipase, protease, and amylase, as well as enzymes produced by the intestinal lining).

D) Esophagus, Stomach, Large Intestine: This option is incorrect because while the stomach does secrete digestive enzymes, the esophagus and large intestine do not. The large intestine primarily absorbs water and salts and does not secrete digestive enzymes.

Answer Explanation

C) small intestine

- Correct: Chemical digestion in humans is a complex process involving various enzymes acting on different nutrients. While digestion does begin in the mouth with the action of enzymes like salivary amylase on carbohydrates, the majority of chemical digestion occurs in the small intestine. Enzymes secreted by the pancreas (such as pancreatic amylase, lipase, and proteases) and the small intestine itself (such as maltase, sucrase, lactase, and peptidases) break down carbohydrates, fats, and proteins into smaller molecules. Additionally, bile salts produced by the liver and stored in the gallbladder aid in the emulsification and digestion of fats in the small intestine. Therefore, chemical digestion largely concludes in the small intestine before nutrients are absorbed into the bloodstream.

A) esophagus

- Incorrect: The esophagus is primarily involved in the mechanical process of swallowing, which pushes food down into the stomach. While some minor enzymatic activity may occur due to saliva coating the food during swallowing, significant chemical digestion does not occur in the esophagus.

B) stomach

- Incorrect: While the stomach does play a role in chemical digestion, particularly in the breakdown of proteins by the enzyme pepsin and the denaturation of proteins by hydrochloric acid, the majority of chemical digestion occurs in the small intestine. The stomach mainly serves to mechanically churn food and begin the process of protein digestion.

D) gallbladder

- Incorrect: The gallbladder stores and releases bile produced by the liver, which aids in the emulsification and digestion of fats in the small intestine. However, the gallbladder itself is not directly involved in chemical digestion, and the majority of digestive enzymes are not secreted or stored in the gallbladder.

Answer Explanation

D) pancreas and the gallbladder

- Correct: Both the pancreas and the gallbladder release digestive secretions directly into the small intestine. The pancreas secretes pancreatic enzymes (such as amylase, lipase, and proteases) into the small intestine to aid in the digestion of carbohydrates, fats, and proteins. The gallbladder stores bile produced by the liver, which is released into the small intestine to aid in the emulsification and digestion of fats.

A) salivary glands and the pancreas

- Incorrect: While the pancreas releases digestive secretions directly into the small intestine, the salivary glands secrete saliva into the mouth, which contains enzymes (such as amylase) that begin the digestion of carbohydrates. Salivary glands do not release digestive secretions directly into the small intestine.

B) gall bladder and the lacteals

- Incorrect: The gallbladder stores bile produced by the liver, which is released into the small intestine to aid in fat digestion. Lacteals are lymphatic vessels found in the villi of the small intestine and are involved in the absorption of fats, but they do not release digestive secretions directly into the small intestine.

C) villi and the salivary glands

- Incorrect: Villi are finger-like projections in the small intestine that increase the surface area for absorption of nutrients but do not release digestive secretions directly into the small intestine. Salivary glands secrete saliva into the mouth to initiate the digestion of carbohydrates but do not release digestive secretions directly into the small intestine.