Fisiologi Hati Dan Pankreas-digest13

8/12/2019 Fisiologi Hati Dan Pankreas-digest13

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Liver, Gallblader & Pancreas

physiology

dr. Mustofa, M.Sc


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Liver

Largest internal organ

Receives major blood supply from hepaticportal vein

Brings venous blood rich in nutrients from digestivetract

Hepatocytes

Livers cells

Capable of regeneration


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Liver


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Liver

Functions

1. Metabolic regulation

1. Carbohydrate metabolism

2. Lipid metabolism

3. Amino acid metabolism

4. removal of waste products

5.

Vitamin storage6. Mineral storage

7. Drug inactivation


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Liver

Functions

2. Hematological regulation

1. Phagocytosis and antigen presentation

2. synthesis of plasma proteins

3. removal of circulating hormones

4. removal of antibodies

5.

removal or storage of toxins6. synthesis and secretion of bile


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Liver

Functions

3. Circulatory regulation

4. Growth regulation


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Gallbladder

Attached to surface of the liver

Bile pouch that stores bile

Ducts Hepatic Duct

Cystic Duct

Common Bile Duct


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Gallbladder

Function: Bile storage

Bile modification

Bicarbonate secretion

Bile compasition

Water

Bilirubin

Ion

Cholesterol

Bile salt


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Bile Secretion

Necessary for digestion and absorption oflipidsin small intestine

Mixture of bile salts, bile pigments, andcholesterol

Bile salts emulsify lipids to prepare them fordigestion

Solubilize products of lipid digestion in packetscalled micelles


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Bile Secretion and Recycling

1. Produced and secreted by liver

2. Stored in gallbladder

3. Ejected into small intestine when gallbladder contracts

4. After lipids absorbed, bile salts are recirculated to livervia enterohepatic circulation Absorption of bile salts from ileum into portal circulation

Delivery back to liver5. Extraction of bile salts from the portal blood by

hepatocytes


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Bile Secretion and Recycling


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Pancreas

Exocrine and Endocrine Gland

1. ExocrineAcinar Cells

Secretes essential digestive enzymes throughpancreatic duct into duodenum

2. EndocrineIslets of Langerhans

Secretes insulin and glucagon into blood stream


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Pancreas


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Pancreas


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Pancreatic Secretion

Exocrine pancreas secretes ~1 L/day into duodenum Fluid consists of HCO3

-and enzymes HCO3

-neutralizes H+delivered to duodenum from stomach Enzymatic portiondigests carbohydrates, proteins, and lipids into

absorbable molecules

Structure of Pancreatic Exocrine Glands Comprises ~90% of pancreas

Rest of pancreatic tissue is endocrine pancreas and blood vessels

Acinar Cells Line blind end of branching duct system Secrete enzymatic portion

Ductal Cells Line the ducts Secrete aqueous HCO3

-component


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HCO3-Secretion

Apical membrane of ductal cells contains a Cl--HCO3-

exchanger

Basolateral membrane contains Na+-K+ATPase and a

Na+

-H+

exchanger1. CO2and H2O combine in cells to form H+ and

HCO3-

2. HCO3-is secreted into pancreatic juice by Cl--HCO3

-

exchanger3. H+is transported into blood by Na+-H+exchanger

Absorption of H+causes acidification of pancreatic venous blood


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Regulation of Pancreatic Secretion

Acinar cells (enzymatic secretion) Receptors for CCK and muscarinic receptors for ACh

CCKis most important stimulant I cells secrete CCK in presence of amino acids and fatty acids in

intestinal lumen

AChalso stimulates enzyme secretion

Ductal cells (aqueous secretion of HCO3-)

Receptors for CCK, ACh, and secretin

Secretin(from S cells of duodenum) is major stimulant Secreted in response to H+in intestine

Effects of secretin are potentiated by both CCK and ACh


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Fisiologi Hati Dan Pankreas-digest13

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