GI system

  1. Bile Acids help the following to absorb into the epithelium?
    • -Fat-soluble vitamins
    • -Cholesterol
    • -and some of the long-chain fatty acids
    • (remember only bacteria can produce short chain fatty acids)
  2. Distinguish between the canaliculi and the ductile cells for biliary canals.
    • In the canaliculi, the main function is excreting the bile acids (BSEP) alsong with the phosphatidylcholine (MDR2) and cholesterol (ABC 5 and 8?).
    • Solution is initially HYPERTONIC.

    • When we get into the ductile cells. we Secrete mainly Bicarb and water. HCO3-.
    • and we also need to make sure we absorb the Glucose(Na) and amino acids (Na), to prevent any bacteria from growing into the biliary ducts. Otherwise if bacteria did get in, then you would deconjugate bilirubin and this would cause it to precipitate with calcium, and youd get pigmented stones.
    • also, glutathione is broken down by the ephelial GGT enzyme so that the amino acid products can be reabsorbed.
  3. Where are bile acids absorbed?
    In the terminal Ileum, the kidneys, and the Biliary ductiles

    by Abst (active transporter) that has Na+ and Bile acids in same direction

    Most of the bile acids in the blood is in the conjugated form, whereas for bilirubin it is in the
  4. When conjugated bilirubin gets to the colon....
    it becomes unconjugated (10% of this gets passively re-absorbed), But MOST (90%) is converted to Urobilins and Stercobilins, which goes into the feces, and gives it brown color.
  5. What are some of the modifiers of Basal Metabolic rate?

    • 1. Physiological = tissue growth. (pregnancy, and growth)
    • 2. Pathological
    • --Decreased: fasting, hypothyrodism, hyperthermia
    • --increased fasting: hypercatabolism, and hypermetabolism
  6. How does the sympathetic splanchnics affect the GI?
    They can either directly release NE on alpha 1 and beta-2 , or they can have an indirect effect (which is much more prominent). they release NE, which binds to the pre-synaptic alpha-2 on the post-ganglion parasympathetic Excitatory neurons, and then causes a decrease in their release of Ach and substance P.
  7. Whats difference between Myenteric Plexus of Auerbach, and Submucousal plexus of Meissner?
    Myenteric plexus is in between the circular and longitudinal muscles. It has interneurons and it releases serotonin.
  8. Where and How: Tonic Contractions
    In the LES, Proximal stomach, the ileocecal valve, and the Internal anal sphincter.

    (remember, the internal anal sphincter is usually contracted closed, unless there is reflex repsonse from the distension of the rectum).

    there is a spontaneous, low-level activation of voltage-gated calcium channels.
Card Set
GI system
GI system