Nutrition in animals cbse class seven science

Nutrition in animals

1. 7 Th Grade General Science In Previous Chapter we learned about the mode of nutrition in Plants i.e., Autotrophies and Heterotrophies In previous grades you have also learned that different animals eat different types of food and their adaptation

2. Based on animals feeding habits, there are classified into some categories Categorize the animals given in the boxes under the categories listed in the table MAN GIANT PANDA LION CROW BACTERIA TIGER VULTURE DEER BEAR SHEEP HERBIVORES CARNIVORES OMNIVORES SCAVENGERS DECOMPOSER

3. Chapter – 2 Nutrition in Animals Animals cannot synthesize their own food and hence have a heterotrophic mode of nutrition The food that we eat cannot be utilized instantly to obtain nutrients. It is first broken down into simpler substance that are easily absorbed by the body to provide nutrition.

4. The stages in Heterotrophic nutrition

5. Nutrition in Amoeba Amoeba is a unicellular organism, does not have any special organ for the process of nutrition. Amoeba has finger like extension called Pseudopodia

6. The process of nutrition in Amoeba Amoeba senses the food Pseudopodia surround the food The food is enclosed in a food vacuole (food + water) Digestive juices secreted into the food vacuole Food is digested and nutrients are absorbed and assimilated Undigested waste is expelled

7. Nutrition in Human In human, the various stages of nutrition take place in a tubular organ called the Alimentary canal or Gut. It includes mouth, oesophagus , stomach, small intestine, large intestine and rectum. In addition to these organs such as, salivary gland, liver, gall bladder, and pancreas also help in nutrition Let us discuss the process of nutrition in human body

8.  Ingestion We humans ingest the food through mouth. Biting, chewing and swallowing happen inside the mouth with the help of teeth and tongue

9. Different teeth have different function in breaking down the food. We have 32 teeth. 16 in each jaw

10. INCISORS are sharp and blade like for cutting food. Example- you might use them to bite into an apple. There are 8 incisors, four in each jaw CANINES are strong and pointed for tearing food. Example- you might use them to tear off a piece of tough meat, or chips packet. There are 4 canines, two in each jaw

11. PREMOLARS share features of both canines and molars. Example- You might use them for tearing and grinding food There are 8 premolars, four in each jaw MOLARS are broad and flat on top for crushing and grinding food. Example- you might use them to grind up nutrients There are 2 or more on each side of both jaws

12.  Digestion Digestion is the process by which food is broken down into simpler substances that can be absorbed and used as nutrients. The salivary glands secrete saliva that lubricates and moistens the food to swallow easily

13. The partly digested food i s swallowed through pharynx and goes down the food pipe called Oesophagus The muscles produces wave like contractions called Peristalsis The bolus(Crushed food) is churned in the stomach for further digestion

14. The stomach wall contains gastric glands which secrete gastric juices. Gastric juices consist mainly of water, digestive juices, hydrochloric acid and mucus. Digestive juices break down the proteins in the bolus to simpler particles. Thus protein digestion begins in the stomach The hydrochloric acid kills any bacteria which may enter the stomach with the food and aids digestive juices in the digestion of proteins. Mucus helps to protect the stomach wall from damage due to hydrochloric acid

15. Continuous movement of the muscular walls of stomach churn the food, mixing it with gastric juices and helping to partially digest the food which is called Chyme . It is passed into the small intestine

16. Liver produces bile, which is thick yellow liquid and the gall bladder stores bile. Bile helps to break down fat into easily digestible small droplets Pancreas secrete pancreatic juice that converts S tarch into simple sugars, Proteins into Amino acids, Fats into fatty acid and glycerol

17. Note: Amino acids are the building blocks of proteins, which are the vital part of a diet. Final products of digestion

18.  Absorption After digestion, Chyme passes into the small intestine. The walls of the small intestine contain fold that provide a large surface area, thereby making small intestine a well suited for the function of absorption. The inner walls of small intestine also have millions of finger like projections called VILLI (as shown in figure)

19. The chyme is moved along the small intestine and the villi absorbs the nutrients in it. The Villi facilitates the transportation of nutrients to our body through blood

20.  Assimilation The liquid chyme is then passed into large intestine , where water and minerals are absorbed. Most of the nutrients have been absorbed in the small intestine, the remaining intestinal content called faeces passes long the large intestine.

21.  Egestion The last part of the large intestine called Rectum, stores the faeces for some time. Faeces are then passed out from the body through anus as stool. The act of expelling the faeces is called egestion or defecation

22. Quick Review of the nutrition in Human

23. Nutrition in Ruminants Grass eating animals with a special type of digestive tract that chew partly digested food a second time in order to soften it are called Ruminants

24.  Ingestion Ruminants have sharp incisors and large molar to bite off and chew plant fibres with the help of tongue, and by mixing it with saliva. Ruminants such as cattle do not have incisors on the upper jaw. They have dental pads instead.

25.  Digestion The chewed food is passed through Oesophagus . The stomach of ruminants has four chambers: 1. rumen 2. reticulum 3. omasum 4. abomasum

26. When the plants food is swallowed for the first time, micro-organism present in rumen and reticulum convert it to simpler forms. The partly digested cellulose is called cud The process of re-chewing the cud to further break down plant matter and facilitate digestion is called rumination or chewing the cud

27. When the cud is swallowed again, it re-enters the rumen and reticulum for further digestion by the action of micro-organisms. The cud then goes into omasum . It acts as strainer, breaks the large particles and pass the digested into the abomasum .

28.  Absorption Absorption of nutrients first occurs when cud passes to the small intestine from abomasum . Digestive juices from liver and pancreas help in breaking down carbohydrates into sugar, proteins into amino acids, and fats into fatty acids.

29.  Assimilation After digestion and absorption, nutrients from food are taken to the cells in all parts of the ruminant’s body  Egestion The undigested food is excreted as faeces through the anus.

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