Nutrition in Animals notes for science class 6 NCERT, PSTET and CTET

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Nutrition meaning:

The process by which organism consume food and use it for bodily purpose is called as Nutrition.

The breakdown of complex components of food into simpler form is called as Digestion.

DIFFRENT WAYS OF TAKING FOOD

Scraping, chewing, siphoning, capturing and swallowing, sponging, sucking etc.

Bees and humming-birds suck the nectar of plants

Infants feed on mother’s milk.

Snakes like the python swallow the animals they prey upon. Some aquatic animals filter

tiny food particles floating.

What is Digestive system?

The digestive tract and the associated glands together constitute the digestive system.

Digestive tract is a canal comprises of various parts

like-buccal cavity, esophagus, stomach, small intestine, large intestine and anus.

The digestive tract is associated with the various glands.

Components of Digestive system.

The mouth and buccal cavity

Food is taken into the body through the mouth. Food with the help of teeth break down mechanically into small pieces.

The saliva in our mouth breaks down the starch into sugars by an enzyme Amylase.

The stomach

The stomach is a thick-walled bag. Its shape is like a flattened J and it is the widest part of the alimentary canal.

The inner lining of the stomach secretes mucous, hydrochloric acid and digestive juices.

The digestive juices break down the proteins into simpler substances.

Liver

The liver is a reddish-brown gland situated in the upper part of the abdomen on the right side.

It is the largest gland in the body.

It secretes bile juice that is stored in a sac called the gall bladder.

The bile plays an important role in the digestion of fats.

Pancreas

The pancreas is a large cream coloured gland located just below the stomach.

The pancreatic juice acts on carbohydrates, fats and proteins and changes them into simpler forms.

The small intestine

The small intestine is highly coiled and is about 7.5 metres long. It receives secretions from the liver and the pancreas.

It also secretes juices.

The carbohydrates get broken into simple sugars such as glucose, fats into fatty acids and glycerol, and proteins into amino acids.

The inner walls of the small intestine have thousands of finger-like outgrowths. These are called villi.

The villi increase the surface area for absorption of the digested food.

Large intestine 

The food that remains undigested and unabsorbed enters into the large intestine.

The large intestine is wider and shorter than small intestine. It is about 1.5 metre in length. Its function is to absorb water and some salts from the undigested food material.

Mechanism of Digestion in Humans:

Digestion occurs by four simple steps: INGESTION, ABSORPTION, ASSIMILATION and EGESTION.

The process of taking food into the body is called ingestion.

The food then passes through Oesophagus and enters stomach were the digestive juices break down the proteins into simpler substances.

Next the food enters the small intestine where the food get mixed with secretion of pancreas and liver.

bile juice (stored in gall bladder) from liver plays an important role in the digestion of fats.

The pancreatic juice acts on carbohydrates, fats and proteins and changes them into simpler forms.

In small intestine the carbohydrates get broken into simple sugars such as glucose, fats into fatty acids and glycerol, and proteins into amino acids.

The digested food can now pass into the blood vessels in the wall of the intestine. This process is called absorption.

Villi in small intestine increases the surface area and helps in better absorption of food.

The absorbed substances are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by the body. This is called assimilation.

The food then enters the large intestine.

The remaining waste passes into the rectum and remains there as semi-solid faeces.

The faecal matter is removed through the anus from time-to-time. This is called egestion.

Link for the lecture

https://youtube.com/shorts/-CCHKOc0O0A?feature=share



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