Question

(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?

Answer 1

Part A: Organs of the alimentary system:

1. Mouth with salivary glands.
2. Esophagus
3. Stomach
   
4. Liver - Digestive gland
5. Gallbladder
   
6. Pancreas - Digestive Gland
7. Small intestine
   
8. Large intestine
9. Anus​

Part B:

Digestion of carbohydrate:

1. Digestion of carbohydrate starts from the mouth where salivary amylase is secreted.
   
2. Salivary amylase partially digests the carbohydrate and then the pancreatic amylase which is secreted in the small intestine completely digests the carbohydrate to convert it into monosaccharides.
   

Digestion of proteins:

1. Protein digestion starts at the stomach due to the presence of pepsin which partially digests the protein.
   
2. Complete digestion occurs in the presence of trypsin and chymotrypsin which is secreted in the small intestine and protein is converted to small peptides and amino acids.
   

Digestion of fats:

1. Fat digestion occurs in the small intestine due to the presence of the enzyme pancreatic lipase.
   
2. The lipase enzyme breaks down the fats into fatty acids and glycerol.
   
3. The bile secreted from the liver helps in emulsification of fats and after digestion of fats the absorption occurs through the walls of the intestine. ​