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Composition and Functions of Pancreatic Juice, Enzymes - Coggle Diagram

- - - - 7.8 to 8.4,
        markedly alkaline due to high HCO3- concentration;
        
        approx. 120 mEq/L;
        4-5 times that of plasma HCO3- concentration.
        -Thus pancreatic juice along with alkaline bile
        
        neutralizes the gastric acid and
        
        helps in raising the pH of the duodenal contents.
        
        Failure to neutralize the acid
        as it enters the duodenum
        will result in duodenal ulcer.
      - Water:
        
        98%
        
        Electrolytes
        
        Cations
        
        Na+, K+ , Ca2+, Mg2+, Zn2+
        
        anions
        
        HCO3-, Cl- and traces of SO42-, HPO42-
        
        Electrolytic composition varies with rate of secretion.
        
        secretory rates
        
        At low secretory rates
        
        HCO3- concentration is
        as high as 80 mEq/L
        
        at high secretory rates.
        
        which increases to 120 mEq/L
        
        cl- & HCO3-
        conc
        
        Cl- concentration falls as HCO3- conc rises
        
        the total conc of these two anions remains constant.
        
        Na+ and K+
        concentrations
        
        2 more items...
        
        Pancreatic secretion involves
        chemical work and is associated with an
        increased O2 consumption.
        The duct cells of the pancreas contain
        carbonic anhydrase (CA) and form the HCO3- which is secreted into the duct lumen.
        HCO3- are formed via the same reaction that occurs
        in the parietal cells of the stomach.
- - - - converts cholesterol esters
        to cholesterol.
      - Pancreatic pro-phospholipase A2
        
        It is secreted in inactive form
        and gets converted to
        phospholipase A2 (active)
        by trypsin.
        This splits a fatty acid off lecithin
        (i.e. phospholipid, a normal constituent of bile)
        forming lysolecithin,
        which
        damages cell membrane.
        
        Pancreatic proteolytic enzymes
        
        Trypsinogen
        
        Trypsin is the most powerful proteolytic enzyme of the pancreatic juice.
        It hydrolyses proteins by splitting bonds in the protein
        molecule which contain L-lysine and L-arginine in which ε-amino or guanidino groups are free.
        Therefore, proteins are digested mainly
        to small polypeptides.
        Some amino-acids are also formed, because
        trypsin can hydrolyse some dipeptides.
        
        Chymotrypsinogen
        
        It digests protein to small polypeptides.
        
        Ribonuclease
        
        Deoxyribonuclease:
        
        2 more items...
        
        Trypsin inhibitor
        
        It is secreted by the same acinar cells and at the
        same time as pancreatic pro-enzymes.
        
        It protects the pancreas from
        ‘autodigestion’.