Digestion and Nutrition

4 Stages of Food Processing

  1. Ingestion

    1. Swallowing

    2. Saliva: lubrication + enzyme

  2. Digestion

    1. Mechanical: 

      • Chewing optional; teeth, radula, mandibles

      • Churning & mixing: stomach, gizzard, crop, rumen

    2. Chemical: Digestive enzymes

      1. Proteins: pepsin, trypsin, peptidases

      2. Carbohydrates: amylase, disaccharidases

      3. Fats: lipase, bile salts

    3. How the body protects itself from its own digestive juices

      1. Digestive compartments

      2. Mucus

      3. Enzymes secreted as precursors

  3. Absorption

    1. Fat-soluble nutrients pass through membrane

    2. Transporters carry sugars, amino acids

    3. Water absorption by osmosis

  4. Elimination

    1. Reflexes

The human digestive system

  1. Mouth
    1. Mastication
    2. Saliva
    3. Amylase
  2. Salivary glands (3)
  3. Esophagus
    1. Swallowing
    2. Epiglottis
    3. Sphincters
  4. Stomach
    1. Churning
    2. HCl Acid production
    3. Digestive enzymes: Pepsin
  5. Small intestine
    1. Folds, villi and microvilli: surface area!
    2. Mixing & peristalsis
    3. Absorption of nutrients
    4. Digestive enzymes: disaccharidases
  6. Pancreas
    1. Bicarbonate
    2. Digestive enzymes: trypsin, peptidases, amylase, lipase
  7. Gallbladder
    1. Bile
  8. Liver
    1. Produces bile
    2. Processes nutrients after absorption
  9. Large intestine
    1. Absorption of water
  10. Rectum & anus

Nutrition

  1. Feeding patterns
  2. Essential nutrients
  3. Homeostasis and nutrient balance
Applications
  1. Malnutrition & obesity
  2. Caprophagy
  3. Stomach ulcers
  4. The role of bacteria in digestion
  5. Ruminants
  6. Department of Agriculture's new food pyramid