The digestive system part 7

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The digestive system part 7
2013-05-22 17:18:51
digestive system part

The digestive system part 7
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  1. lacteal
    a lymphatic capillary found in the villi
  2. microvilli
    are projections of the apical(free) membrane of the absorptive cells. Each projection contains a bundle of actin filaments.  When viewed under a microscope they form a fuzy line called the brush border
  3. intestinal juice
    a clear yellow fluid that contains water and mucous and is slightly alkaline. Together with pancreatic juices they provide a liquid medium that aids the absorption of substances from chyme.
  4. brush border enzymes
    digestive enzymes synthesized by the absorptive cells.  They insert themselves in the plasma membrane of microvilli.  Thus some enzymatic digestion occurs at the surface of absorptive cells
  5. segmentations
    localized mixing contractions that occur in portions of intestine distended by a large volume of chyme.  They mix chyme with the digestive juices and bring the particles of food into contact with the mucosa for absorption.  They do not push food along the tract
  6. migrating motility complex
    the type of peristalsis that occurs in the small intestine.  Takes 90-120 minutes for one to move from the stomach to the ilieum
  7. enzymes that digest carbs
    salivary amylase, pancreatic amylase, a-dextrinase, sucrase, lactase, maltase
  8. enzymes that digest proteins
    pepsin, peptidase, aminopeptidase, dipeptidase, pancreatic juice
  9. enzymes that digest lipids
    lipases, bile salts
  10. enzymes that digest nucleic acids
    pancreatic juice, nucleosidases phosphates
  11. absorption
    passage of digestive nutrients from the GI into the blood or lymph
  12. absorption of monosaccarides
    all carbs are absorbed as these.  They are absorbed via facilitated diffusion or active transport
  13. absorption of amino acids, peptids
    proteins are absorbed as these via active transport processes that occur mainly in the duodenum and jejunum.
  14. absorption of lipids
    all of these are absorbed via simple diffusion.  Broken down into monoglycerids and fatty acids.
  15. miscelles
    tiny spheres formed around long chained fatty acids and monoglycerids by bile salts.  These ferry fatty acids to absorptive cells
  16. chylomicrons
    large spherical masses of triglycerides, phospholipids and cholesterol coated with protein.  These are formed inside absorptive cells
  17. lipoprotein lipase
    breaks down triglycerids in chylomicrons and other lipoproteins into fatty acids and glycerol.  This enzyme is attached to the apical surface of capillary endothelial cells
  18. enterohepatic circulation
    the cycle of bile salt secretion by the hepatocytes into bile, reabsorption by the ileum and resecretion into bile
  19. absorption of electrolytes
    many come from GI secretions.  They are actively transported