Nutrition in Animals

Overview

• Nutrition in Animals: Class 7 Science chapter
• Autotrophs vs Heterotrophs:
  • Autotrophs: Plants make their own food.
  • Heterotrophs: Animals depend on other organisms for food (Holozoic Nutrition).

Steps of Holozoic Nutrition

1. Ingestion: Taking in food.
2. Digestion: Breaking down food into smaller, simpler substances.
3. Absorption: Nutrients absorbed into the blood.
4. Assimilation: Utilizing absorbed nutrients in body processes.
5. Egestion: Excreting waste materials from the body.

Key Definitions

• Ingestion: The process of taking in food.
• Digestion: Breaking down food into simple, soluble molecules.
• Absorption: Entry of digested food into the bloodstream.
• Assimilation: Use of absorbed nutrients by the body.
• Egestion: The expulsion of undigested food.

Human Digestive System

• Elementary Canal: A long tube from mouth to anus.
• Mouth:
  • Teeth: Chew food (Milk teeth in children replaced by permanent teeth).
  • Saliva: Contains salivary amylase, starts carbohydrate digestion in the mouth.
  • Mastication: The process of chewing food.

Tongue

• Function: Helps in chewing and mixing food with saliva; contains taste buds.

Pharynx and Esophagus

• Pharynx: Connects mouth to esophagus.
• Esophagus: Tube that carries food to stomach.
• Epiglottis: Flap that prevents food from entering the windpipe.

Stomach

• J-shaped Organ: Contains glands that secrete hydrochloric acid and pepsin for digestion.
• Digestion: Food is churned and mixed with digestive juices.

Small Intestine

• Main Site of Digestion: Completes the breakdown of food into simpler molecules (e.g., carbohydrates into glucose).
• Pancreas: Produces pancreatic juice for digestion.
• Liver: Produces bile, stored in gallbladder, helps digest fats.

Villi in Small Intestine

• Structure: Millions of finger-like projections that increase surface area for absorption.

Large Intestine

• Function: Absorbs water and stores undigested food before excretion.

Nutrition in Ruminants (Grass-Eating Animals)

• Ruminants: Animals like cows with four stomach chambers.
• Digestion Process:
  1. Initial ingestion without thorough chewing.
  2. Food is stored in rumen, then chewed again (rumination).
  3. Digestion of cellulose aided by specific bacteria.

Nutrition in Amoeba

• Unicellular Organism: Captures food using pseudopodia (false feet).
• Nutrition Process:
  1. Ingestion: Engulfs food particle.
  2. Digestion: Occurs in food vacuole.
  3. Absorption: Nutrients absorbed for energy and reproduction.
  4. Egestion: Expulsion of undigested material.

Recap of Key Processes in Nutrition

• Five Steps of Nutrition:
  • Ingestion, Digestion, Absorption, Assimilation, Egestion.
• Human Digestive System Components: Buccal cavity, pharynx, esophagus, stomach, small intestine, large intestine.
• Ruminant Digestion Features: Multi-chambered stomach, rumination process.
• Amoeba's Unique Digestion: Uses pseudopodia for food capture.

Frequently Asked Questions

1. Steps of Nutrition: Ingestion, Digestion, Absorption, Assimilation, Egestion.
2. Stomach Juices: Hydrochloric acid and digestive juices.
3. Villi Location and Function: Present in small intestine, increase absorption surface area.
4. Bile: Produced in liver, aids in fat digestion.
5. Large Intestine Function: Absorbs water, stores undigested food.
6. Chewing: Done in the mouth (buccal cavity).

Conclusion

• Importance of understanding nutrition processes in animals for overall biological education.