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Digestive System - Coggle Diagram

- - - - Juice contains:
        
        Bile produced by the liver and stored in the gallbladder;
        
        Trypsin (protease), lipase, amylase and bicarbonate from the pancreas
        
        Its own cells produce:
        
        Nuclease
        
        Maltase
        
        Lactase
        
        Scurase
        
        Exopeptidases
        
        DIpeptidases
    - - The jejuno's mucosa is made up of thousands of villi
        
        this greatly increases the surface area
        
        Each cell lining the villus is full of protections of the plasma membrane called microvilli
    - - Pancreatic amylase breaks down 1,4 bonds in starch molecules at least 4 glucose molecules long
      - 1,6 bonds in amylopectin (or shorter molecules called dextrins) are broken by:
        
        Maltase (acts on maltose)
        
        Glucosidase (acts on maltotriose)
        
        Dextrinase (acts on dextrins)
        
        (these enzymes are found in the membrane of microvilli)
  - - - and will be eliminated in feces
      - With the exception of water, which is mostly absorbed here
    - - Important because of the production of vitamin K by these organisms
- - - - Pepsin: protease with acidic optimum pH (pH 2).
      - Hydrochloric acid (HCl): helps killing pathogens, breaks down some food and provides the optimum pH for pepsin.
      - Mucus: protects gastric cells from the hydrochloric acid.
  - - - Amylase: starch into maltose
      - Lipases: trglycerides into fatty acids and glycerol or monoglycerides
      - Proteases: proteins and polypeptides into oligopeptides
      - Bicarbonate
  - - - Villi increase the surface area for absorption of nutrients
        
        nutrients absorbed:
        
        Monomers formed in digestion
        
        Monosaccharides
        
        glucose
        
        fructose
        
        galactose
        
        others
        
        Mineral ions
        
        Vitamins
        
        Most molecules absorbed go into the capillary bed
        
        Capillary vessels in villi have larger pores than normal
        
        to aid in the passage of nutrients
        
        Fatty acids are more efficiently absorbed into the lacteal
        
        Lacteal: part of the lymphatic system
      - Important to absorb as many nutrients as possible in the jejuno
      - Blood flow
        
        Blood arrives at the villus through arterioles (which branch into capillaries)
        
        Capillaries collect the nutrients absorbed in the villus and fuse into venules
        
        Blood carrying glucose and other nutrients leave the villus through venules
        
        Blood is then transported to the liver
        
        by the hepatic portal vein
        
        where excess glucose can be absorbed by liver cells and converted to glycogen
- - - - by simple diffusion
    - - forming lipoproteins
        
        then the lipoproteins are transported out of the cell by exocytosis into the inner part of the villus and are collected by the lacteal