Human Digestive System

General Terms
1. Digestion
  1. The physical and chemical process by which food is broken down into smaller, soluble molecules that can be absorbed into the bloodstream
    1. Physical digestion
      1. The mechanical action of teeth, jaw and muscle movement
        Mouth
        Mastication
        Chewing using teeth and jaw movement
        Muscle
        Peristalsis
        Oesophagus
        Small intestine
        Contractions in stomach wall
        Other
        Small intestine
        Bile emulsifying fat
      2. Breakdown of large food molecules into smaller molecules
        Increases surface area
        Increases efficiency of chemical digestion
    2. Chemical digestion
      1. Action of enzymes and gastric juices
        Mouth
        Amylase enzyme
        Stomach
        Gastric fluids
        Small intestine
        Pancreatic juice
2. Enzymes
  1. Complex proteins folded into specific shapes
    1. Have an active site
      1. Only fits a specific substrate
  2. Helps break down large food molecules into smaller, soluble molecules that can be absorbed into the bloodstream by catalysing chemical reactions in the digestive system
Mouth
Stomach
1. Lined with gastric pits
  1. Produces gastric fluids
    1. Hydrochloric acid (HCl)
      1. Acidic (pH 1-2)
    2. Mucus
      1. Protects stomach lining from corrosive nature of the HCl
    3. Pepsin
      1. A protease
        Catalyses the breakdown of proteins into polypeptides
        Liquifies the food into chyme
        Semi digested food
2. Large, elastic walls
  1. Can hold 2-4 L of food
    1. Meal can be ingested quickly and digested slowly
  2. Muscular contractions of stomach walls
    1. Churns food
    2. Thoroughly incorporates food with gastric fluids
Small Intestine
Large Intestine

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Human Digestive System

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	Created by J. Po almost 7 years ago