Chapter 2: Digestive System

• 5 Main Processes when breaking down food

  1. Ingestion
  2. Digestion
  3. Egestion
  4. Absorption
  5. Assimilation
• The digestive system diagram


  The diagram 👇

  
• Ingestion


  Taking food and drink into the body through the mouth
• How does food move along the Digestive System

  Muscles move food through the digestive system

  Peristalsis

  Circular muscles and longitudinal muscles contract and relax in turns to move food along
• Digestion


  Breakdown of large, insoluble food molecules into small, water-soluble food molecules so that they can be absorbed into the bloodstream
• Mechanical Digestion - What & Where


  Breakdown of large pieces of food into smaller pieces of food without changing the food molecules
• Chemical Digestion - What and Where


  Breakdown of large food molecules into smaller molecules by action of enzymes
• Absorption


  Movement of digested food molecules through the wall of the small intestine (ileum) into the blood
• Adaptations of the small intestine for efficient absorption

  Large surface area

  Thin lining (one cell thick)

  Moist lining

  Rich blood supply
• Absorption - Villi


  Adaptations of the small intestine for efficient absorption

  Folded inner lining with millions of tiny, finger-like projections called villi

  Digested food reaches capillaries and lacteals (lymph capillaries) in villi

  Absorbed food molecules transported to liver by hepatic portal vein
• Assimilation


  Absorbed food molecules become part of cells or used by cells
• Egestion


  Passing out of indigestible food through the anus

  Feces - solid waste