Pancreatic juice...

Pancreatic juice, Biochemistry, Physiology!!
pancreatic enzymes, regulation secretions...

1. PANCREATIC JUICE “E Group 18LM” By: Sandeep Ganguani

2. PANCREATIC JUICE Transparent isotonic Fluid secreted from pancreas Dual Nature: Secretions from both Endocrine And Exocrine cells Daily Secretions: 1000-1500ml basal rate: 0.2-0.3ml/min, Stimulated phase: 3ml/min pH: 8-9 Normal, slightly alkaline Properties:

3. Endocrine Secretions: Harmones Exocrine Secretions : Histologically resemble salivary glands. Digestive Enzymes (secreted by acinar cells)

4. Pancreatic Juices Secretory Phases: Three phases Cephalic phase (20% secretions) Gastric Phase (10% secretions) During cephalic and gastric phases secretion contains lesser quantity of water, but sufficient solid compounds; so hardly reaches the Duodenum. cephalic and gastric phases are under control of ANS, ( Vagus nerve through releasing Neurotransmitter AcetylCholine) Parasympathatic: increases secretions Sympathetic: decreases secretions.

5. 3. Intestinal phase : 70% of secretions are released during this phase. Intestinal phase of pancreatic secretions is mostly under Harmonal control. Contains higher conc: of water and Bicarbonate ions and rich in enzymes and and other solids Physiological actions of pancreatic juice are performed during this phase.

6. Composition: 98-99% water 1-2% Solids Solids, having both organic(1/3rd) and inorganic(2/3) compounds.

7. Solids: Inorganic Ions: Major Ions: Bicarbonate Ions Na Ions
K Ions Cl ions Minor Ions: Mg ions Phasphorous

8. Bicarbonate Ions: Secreted by Duct epithelial cells. Secreted 5 times more that of plasma Functions: Neutralise acidic pH of Chime coming from stomach. Block Digestive Active substances of gastric juice. Provide proper pH for functions of pancreatic enzymes.

9. Solids: Organic: Mainly Enzymes: Amylase, Lipase, Protease and trypsin inhabitor

10. Pancreatic α - Amylase: Active form, acts on polysaccharides (glycogen and Starch). Hydrolyses α 1_4 glycosidic linkage of polysaccharide chain. Cofactor: Cl ions function as increasing the activity for Pancreatic Amylase. Inhabitor: Gastrin Harmone Optimum pH: 7.1 Note:- pancreatic amylase differs from salivary amylase in performance medium, Salivary amylase is most active on pH of 6.8

11. Proteases: Following enzymes, acting on proteins are found in Pancreatic Juice: Trypsin Chymotrypsin Carboxy_peptidases Amino_peptidases Elastases Collagenase

12. Trypsin: Basically secreted in inactive form Trypsinogen. Enterokinase of duodenal secretion activates Trypsinogen to trypsin. Trypsin thus activated by enterokinases, activates other pancreatic enzymes. Hydrolyses proteins to proteoses and polypeptidases. Functions as Blood Clotting activating prothrombin to thrombin. pH: 8_9

13. Chymotrypsin: _Released as inactive form Chymotrypsin. _Trypsin activates Chymotrypsin into trypsin. _ Causes Milk coagulation Note:- The main  difference between chymotrypsin  and  trypsin  is the amino acids they select for.  Chymotrypsin  is the enzyme that selects for the aromatic amino acids: phenylalanine, tryptophan, and tyrosine.  Trypsin  is the enzyme that selects for the basic amino acids: lysine and arginine.

14. Lipolytic Enzymes Pancreatic Lipase Cholestrol estrase Phospholipase A2 Co-Lipase Bile salt activated Lipase

15. Pancreatic Lipase: Act on fat globules after they are emulsified Major enzyme causes hydrolysis of tryglycerides into monoglycerides and fatty acids. Activators: Bile salt, soaps, synthetic detergents Inactivated by acid enviornment pH: 8.2_9.2 This is water soluble enzyme.

16. Regulation of Pancreatic Secretion_ Intestinal Phase Pancreatic secretions during intestinal phase are mostly under Harmonal Control. Two major harmones basically control pancreatic secretions: Secretion Cholesystokinin (CKK)

17. Regulation of Pancreatic Secretion_ Intestinal Phase Secretin: secreted by S_cells of duodenal mucosa. stimulus: HCL of gastric juice coming with chyme. Increases secretion of watery alkaline solution from pancreas (especially Bicarbonate ions ) Increases the activity of CCK.

18. Regulation of Pancreatic Secretion_ Intestinal Phase 2. Cholecystokinin(CCK) Secreted from I cells of duodenal mucosa. Stimulus: diet of good proteins and fats stimulates secretion of pancreatic juice rich in enzymes and lower water conc: Delays gastric emptying. Increases the action of Secretin.

19. Applied Aspects Acute Pancreatitis: acute inflammatory disease due to autodigestion of pancreatic tissue by proteolytic enzymes. Chronic Pancreatitis: Chronic inflammation Cystic Fibrosis: Decrease pancreatic enzyme leads to Steatorrhoea .

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