Class 7 Chapter -2 Notes on Nutrition in Animals

Notes on Nutrition in Animals

·   The animals depend upon other plants and animals for their food.

·    Animal nutrition comprises the mode of taking in the food in the body, nutritional requirements of the body and how animals can utilize their food.

·    Digestion - it is a process by which animals break down complex food substances in simpler substances.

Different ways of taking the food

Digestion in Humans

·       The food that we eat passes through a Canal inside our body.

·       The food is processed and utilized in the body and unused food is collected inside the canal only.

·       This Canal is often called as the Alimentary Canal or the Digestive Tract.

·       The canal is divided into different parts:

o    The Mouth or Buccal Cavity

o    Food Pipe or Oesophagus

o    Stomach

o    Small Intestine

o    Large Intestine

o    Anus

 

There are three glands associated with the alimentary canal that secrete digestive juices that are used to convert the complex food substances into simpler substances.

·       liver

·       pancreas

·       salivary glands

The Digestive System - The alimentary canal and the digestive glands together form a system in the human body which is responsible for the digestion of food in the body. This system is called     the Digestive System.

Ingestion - the process of taking in the food through the mouth is called ingestion.

·   The food is chewed with the help of teeth, saliva and the tongue present in the mouth.

·  The salivary glands present in our mouth secrete saliva which mixes with the food, moist it and breaks the starch present in the food into sugar.

·       The tongue present in the mouth helps in mixing the food with the saliva and helps in swallowing it inside the mouth. It also has taste buds which help in identifying the taste of anything that we eat. Besides this, the tongue also helps in talking.

The Teeth

Milk Teeth - In the early childhood a set of teeth growth in children that then fall off after certain age 6 to 8 years. These teeth are called Milk Teeth.

Permanent Teeth - The teeth that grow after milk teeth fall off are called Permanent Teeth. They generally remain during the lifetime of a person or at least until old a

Tooth Decay –

·       A gradual damage of teeth is often called tooth decay.

·       The main cause of tooth decay is the presence of bacteria in the mouth that grow if we do not keep our mouth and teeth clean.

·       Any leftover food present inside our teeth is broken down by such bacteria.

·       As a result, an acid is released which damages the teeth slowly.

·       Tooth decay can cause severe pain and even toothless.

·       Tooth decay is caused mainly because of eating food with high sugar content, soft drinks and choc

How can we prevent tooth decay?

·       Clean your teeth with a brush or dental floss at least twice a day

·       Rinse your mouth after every meal you eat

·       Do not put a dirty finger or any unwashed food items in your mouth

Food Pipe or Oesophagus

·       The food pipe starts from the neck region and runs until the chest area in animals.

·       The food, when the chewed, moves through the food pipe and reach the stomach through this path.

·       The food moves in download direction in the food pipe.

The Stomach

·       It is the widest part of the alimentary canal.

·       It's a bag like structure in a flat U shape.

·       The stomach is connected with the food pipe and the small intestine.

·       The stomach’s inner lining produces three things:

     o    Mucous: It protects the stomach lining

o    Hydrochloric Acid: It kills the bacteria present inside the stomach and activates the digestive juices

o    Digestive Juices: They help in digestion of the food by breaking down the proteins present in the food into simple substances.

Small Intestine

·       It is a highly coiled structure.

·       The length of the small intestine is almost 7.5m.

·       The liver and pancreas release digestive juices into the small intestine.

·       The inner lining of the intestine also secretes some digestive juices on its own.

·       The small intestine breaks the carbohydrates into glucose, fats into fatty acids and proteins into amino acids.

The Liver

·       It is a gland reddish brown in colour.

·       It is known as the largest gland of the human body.

·       It secretes a digestive juice called bile juice.

·       The bile juice is stored in the gallbladder.

·       The bile juice makes it possible for the body to digest the fats.

The Pancreas

·       It is a cream coloured gland present in the human body.

·       It secretes pancreatic juice that helps in digestion of fats, carbohydrates and proteins.

How small intestine absorbs food?

·    Absorption: it is a process by which the digested food enters the blood vessels of the small intestine.

·    Villi in the intestine: the small intestine contains small finger-like structures called Villi. They increase the surface area of the intestine thereby increasing the amount of absorption. The digested food gets into the blood vessels through villi and then reaches the whole body.

Summary of digestion 

Link of Chapter -1 Nutrition in plants