Question

Essentially the word digestion means
A: Burning of food
B: Oxidation of food
C: Hydrolysis of food
D: Breakdown of food

Answer 1

Digestion is the complete conversion of complex substances into a much simpler form, so that can be easily digested. It carries out its processes with the help of different enzymes and certain digestive acids. Indigestion processes the fats get converted to fatty acids and carbohydrates into glucose.

Complete step by step answer:
Digestion is breaking down large food molecules into tiny molecules. Tiny molecules are easily absorbed in the blood. Digestion mainly consists of two processes :
a. Mechanical digestion: Physical breakdown of big food molecules into small ones
b. Chemical digestion: Digestive enzymes break down food in molecules which can be absorbed by the body
Process of digestion: Mechanical digestion starts in the mouth i.e., mastication using saliva secreted by salivary glands. Saliva also aids in starch digestion and food becomes a slurry mass called a bolus. Food now reaches the stomach through the oesophagus by peristalsis. The stomach secretes HCl and pepsin which starts protein digestion. After digestion in the stomach, the food becomes chyme which moves to the duodenum by the opening of the pyloric sphincter. Enzymes from the pancreas and bile juice from the liver reach the duodenum. Further digestion by enzyme succus entericus and absorption occurs in the small intestine. Then in the large intestine water and minerals are reabsorbed and waste is eliminated through the rectum.
Hence, option D is correct answer.

Note: As the food moves through various organs in the digestive system it is broken down into simpler and simpler molecules which are absorbed in the end. Starch digestions occur in the mouth and small intestine and protein digestion occurs in the stomach and small intestine. 90% of food molecules are absorbed in the small intestine. Rest absorption of water and minerals occurs in the large intestine and the waste is released from the rectum as feces.