(a) Name the main organs of the human digestive system. Also name the associated glands. (b) How do carbohydrates, fats and proteins get digested in human beings?

• The digestive system consists of an alimentary canal and glands associated with it. The organs involved in the alimentary canal are mouth, esophagus, stomach, small intestine and large The glands associated with it are salivary glands, liver and pancreas.
• Carbohydrates - The digestion of carbohydrates begins in the Salivary amylase enzyme present in saliva which the starch into maltose sugar. The intestinal juice of the small intestine completes the digestion of carbohydrates and finally converts it into glucose.

Fats - The process of digestion of fats begins in the stomach. The enzyme, lipase breaks down the fats present in the food. From the stomach the partially digested food goes into the small intestine where the pancreatic lipase breaks down the emulsified fats. The walls of small intestine secrete intestinal juice which converts the fats into fatty acids and glycerol.

Proteins - The digestion of proteins begins in the stomach. The enzyme, pepsin converts the proteins into peptones. Pancreatic juice contains trypsin which digests the proteins into peptides and the intestinal juice completes the process of digestion of proteins thus converting it into amino acids.