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DIGESTIVE SYSTEM

Dr. Tamseela Mumtaz

Gastrointestinal Secrections and their control

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Role of pancrease in digestion

Role of pancrease in digestion

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Role of pancrease in digestion

    • Pancreas (Gr. Pan,a all + kreas, flesh) is an organ that lies just ventral to the stomach and has both 1-endocrine (Insuline,Glucagon) and 2- exocrine function
  • Exocrine cells in the pancreas secrete digestive enzyme into the pancreatic duct, which merges with the hepatic duct from the liver to form a common bile duct that enters the duodenum
  • It completes the digestion of carbohydrates and proteins and initiate the digestion of lipids

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    • Trypsin, chymotrypsin and carboxypeptidase digest protein into small peptides and individual amino acids
    • Pancreatic lipase split triglyceride into smaller and absorbable glycerol and free fatty acid
    • Pancreatic amylase converts polysaccharides into disaccharides and monosaccharides(gulucose)
    • The pancreas also secrete the bicarbonate ions that help neutralize the acidic food residue coming from the stomach
  1. Bicarbonate raises pH from 2-7 for optimal digestion (without this neutralization, pancreatic enzymes may not work)

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Role of Liver

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  • Liver is the largest organ in the body, present under the diaphragm
  • In this, millions of specialized cells called hepatocytes takes up nutrients from intestine and release into blood
  • Hepatocyte also manufacture the blood protein prothrombin and albumin

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Role of Liver

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Functions of Liver

  • Some major function includes the following:

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  1. Removal of amino acid from organic compound
  2. Urea formation from proteins and conversion of excess amino acids into urea to decrease body level of ammonia
  3. Manufacture of the plasma proteins, formation of fetal erthrocytes (RBC), destruction of wornout erythrocytes and synthesis of blood clotting agent prothrombin and fibrinogen from amino acids.

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Functions of Liver

4. Synthesis of non-essential amino acid

5. Conversion of galactose and fructose to glucose

6. Oxidation of fatty acid

7. Formation of lipoproteins, cholesterol and phospholipids

8. Conversion of carbohydrate and protein into fat

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Functions of Liver

9. Modifications of waste products, toxic drugs and poisons

10. Synthesis of vitamin A from cerotene and with the kidneys participation in the activation of vitaminD

11. Maintenace of a stable body temperature by raising temperature of the body passing through it (its many metabolic activities make it major heat projector)

12. Manufacture of bile salts( used in small intestine for emulsification and absorption of fats, cholesterol, phospholipids and lipoproteins)

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13. Main storage centre (the liver stores glucose in the form of glycogen, and with the help of insulin and enzymes, converts glycogen back to glucose as the body needs. It also stores fat soluble vitamins and also fats, amino acids and convert the fats and amino acid into glucose)

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Gallbladder

  • Gallbladder is a small organ near the liver
  • It stores the greenish fluid called bile that produced from liver
  • Bile is very alkaline and contain pigments, cholesterol, lecithin, mucin, bilirubin and bile salt that act as detergents to emulsify fats and aids in digestion
  • Bile salts combine with end product of fats and form micelles
  • Micelles are lipid aggregates with surface coat of bile salt

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