Nutrition in Animals | Class 7 | Chapter 2

Nutrition in Animals|Class 7|Chapter 2

Different Ways of Taking Food:

• Each species has its own way of taking in food.
• Bees and hummingbirds suck plant nectars.
• Infants of humans and some animals feed on mother’s milk.
• Snakes like pythons consume animals they prey upon.
• Aquatic animals filter small food particles from the water.

Digestion in Humans:

• The digestive system consists of the digestive tract and associated glands.
• The digestive tract includes the esophagus, stomach, small intestine, and large intestine.
• Major digestive glands are salivary glands, liver, and pancreas.

Buccal Cavity:

• The buccal cavity, or mouth, is the beginning of the digestive system.
• It consists of the tongue and teeth.
• Teeth help in chewing and breaking down food.
• The tongue helps in mixing saliva with food while chewing. 

Oesophagus or Food Pipe:

• It is a muscular tube that transports food from the mouth to the stomach.
• Food is propelled down by the movement of the food pipe’s walls.

Tongue:

• The tongue is a fleshy and muscular organ in our mouth.
• It is attached at the back of the base of the mouth.
• The tongue helps us mix saliva with food while chewing and helps us swallow the food.
• It also has taste buds that allow us to recognize different tastes.

Tooth decay:

• Tooth decay happens when bacteria in our mouth break down the sugars from leftover food.
• This produces acid that slowly damages our teeth and causes tooth decay.
• It’s important to take care of our teeth to prevent tooth decay.

Stomach:

• It is a thick-walled bag-like structure that receives food from the food pipe.
• The inner lining of the stomach produces mucus, hydrochloric acid, and digestive juices.
• In the stomach, food is mixed and churned, forming a partially solid mass.
• Enzymes in gastric juice help in the disintegration of food. 

Small Intestine:

• It is a highly coiled organ of 7.5 meters in length.
• The small intestine gets secretions from the liver and pancreas.
• Complete digestion and absorption of food occur in it.
• The inner walls of the intestine have finger-like outgrowths called villi.
• Villi increase the surface area for the absorption of food.

Large Intestine:

• It is wider and shorter than the small intestine.
• Absorption of water and salt from undigested food occurs in the large intestine.
• Waste matter is passed out through the rectum.
• Faecal matter is removed through the anus in the process of egestion. 

Saliva and Salivary Glands:

• Saliva, secreted by salivary glands, helps in the breakdown of food.
• Saliva contains mucous and salivary amylase.
• Mucous aids in the easy passage of food through the food pipe.
• Salivary amylase breaks down starch into simpler sugars. 

Gall Bladder:

• It is a small pear-shaped organ located under the liver.
• The gallbladder stores bile juice secreted by the liver.
• Bile plays an important role in the digestion of fats. 

Ingestion and Digestion:

• Ingestion is the process of taking food into the body.
• Digestion is the breakdown of complex food components into simpler substances.
• Partial digestion occurs in the stomach, while complete digestion occurs in the intestine. 

Absorption and Assimilation in Small Intestine:

• Absorption is the uptake of digested food by the blood vessels lining the small intestine.
• Assimilation refers to the utilization of absorbed food by various organs to build complex substances like proteins.
• Villi in the small intestine increase the surface area for absorption.

Digestion in Grass-Eating Animals:

• Grass-eating animals have a different digestive system than humans.
• They chew continuously and have a special chamber called the rumen to partially digest food.
• The partially digested food, called cud, is regurgitated and chewed again through rumination.

Feeding and Digestion in Amoeba:

• Amoeba is a single-celled organism found in pond water.
• It captures food particles using pseudopodia in a process called phagocytosis.
• Digestive juices break down food inside a food vacuole, and the digested food is absorbed. 

Visit for more: Nutrition in Plants | Modes of Nutrition