Question

1. Define nutrition. List the 5 steps involved in it.

Answer 1

Nutrition:

1. Nutrition is a method in which the food is consumed by the organisms and utilizing the nutrients from the food.
2. Nutrition is the process of taking in food and converting it into energy and other vital nutrients required for life.
3. The main nutrients are carbohydrates, fat, protein, vitamins, minerals, and roughage.
4. The path from where food passes are called alimentary canal.

Mouth ⇢ Esophagus ⇢ Stomach ⇢ Small intestine ⇢ Large intestine

In human beings, there are five steps of nutrition :

1. Ingestion
2. Digestion
3. Absorption
4. Assimilation
5. Egestion

1. Ingestion:

1. Ingestion is the process in which the food is taken inside the body through the mouth.
2. In the mouth, food is broken down into small pieces and chewed and churned by teeth Saliva is mixed with food by the tongue. In saliva, salivary amylase (ptyalin) enzyme is present which help in the digestion of carbohydrate. Thus, Initial digestion takes place in the mouth by saliva
3. When saliva is mixed with food called bolus.
4. The bolus passes into the stomach through the esophagus.
5. In esophagus, no digestion occurs.

2. Digestion:

(a). In stomach :

1. Break down of food into nutrients and waste is called digestion.
2. Now bolus passes into the stomach.
3. The walls of the stomach secrete a juice called gastric juice (Hydrochloric acid, Pepsin, and Mucus)

• Mucus : It forms the inner lining of the stomach so HCl does not harm the stomach.
• HCl : It kills the germs present in the food and makes the food medium acidic so Pepsin can work.
• Pepsin: It help in the digestion of protein. It converts protein into peptones and proteases.

4. When gastric juice is mixed with the bolus, then it converts into a soup-like medium called chyme.

(b). In small intestine :

1. The chyme passes into the small intestine, where bile juice, pancreatic juice, and Intestinal juice (succus entericus), are secrete.

• Bile juice : It is produced by liver, stored in gall bladder, and secrete in small intestine. Bile juice makes the food medium alkaline and emulsifies the fats.
• Pancreatic juice : It is secreted by pancreas. In pancreatic juice, three enzymes are present- trypsin, lipase, and amylase ,which are essential for digestion of most of the protein, fat, and carbohydrate in the food.

1. Trypsin : It converts proteins into peptides or pentoses.
2. Lipase : It converts fats into fatty acids and glycerol
3. Amylase : It converts carbohydrate (starch) into maltose.

• Intestinal juice (succus entericus) secreted by small intestine in which many enzymes are present which digest the food completely.

3. Absorption :

1. The separated nutrients get absorbed in the blood is called absorption.
2. In this process, a finger-like projections called villi help.

4. Assimilation:

1. The absorbed nutrients utilized by the body cells or tissues is called assimilation.

5. Egestion:

1. The undigested waste expelled out from the body through anus is called egestion.