Chapter 2: Nutrition in Animals

• Introduction

  • Definition of Animal Nutrition
  • Components: Nutrient requirement, Mode of intake, Utilization in body

• Different Ways of Taking Food

  • Scraping (e.g., Ants)
  • Chewing (e.g., Humans, Cows)
  • Siphoning (e.g., Hummingbirds)
  • Capturing and swallowing (e.g., Snakes)
  • Sucking (e.g., Mosquitoes, Leeches)
  • Filter feeding (e.g., Aquatic animals)

• Digestion in Humans

  • Alimentary Canal (Digestive Tract)
    • Buccal Cavity (Mouth)
      • Teeth (Types: Incisors, Canines, Premolars, Molars)
      • Salivary Glands (Produces Saliva containing amylase)
      • Tongue (Tasting, mixing, swallowing)
    • Food Pipe (Oesophagus)
      • Peristalsis (Wave-like muscle movement)
    • Stomach
      • J-shaped bag
      • Secretes Hydrochloric acid (HCl), mucus, and digestive juices
    • Small Intestine
      • Highly coiled, about 7.5 meters long
      • Receives secretions from Liver (Bile) and Pancreas (Pancreatic juice)
      • Villi (Finger-like projections for absorption)
    • Large Intestine
      • Wider and shorter (about 1.5 meters)
      • Absorbs water and salts
    • Anus
      • Egestion of faeces
  • Ingestion, Digestion, Absorption, Assimilation, and Egestion

• Digestion in Grass-Eating Animals (Ruminants)

  • Rumen (Special part of stomach)
  • Cud (Partially digested food)
  • Rumination (Returning cud to mouth for chewing)
  • Rich in Cellulose (Plant carbohydrate digested by bacteria)

• Feeding and Digestion in Amoeba

  • Single-celled microscopic organism
  • Pseudopodia (False feet) for movement and capturing food
  • Food Vacuole (Where digestion takes place)
  • Egestion of waste through the cell membrane