Digestive system Histology

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Digestive system IV : 

Digestive system IV Liver & Pancreas

Liver and biliary system : 

Liver and biliary system

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Develops embryological as a glandular outgrowth of the primitive gut. 2% of body weight Second heaviest organ of body Irrigated by two type of blood vessels Portal vein (70%) Hepatic artery (30%)

Major function of liver : 

Major function of liver Fat metabolism Oxidizing triglyceride to produce energy Synthesis of plasma lipoproteins. Synthesis of cholesterol and phospholipids. Carbohydrate metabolism Converting carbohydrate and protein in fatty acid and triglyceride. Regulation of blood glucose concentration by glycogenesis, glycogenolysis and gluconeogenesis.

Major function of liver : 

Major function of liver Protein metabolism Synthesis of plasma proteins , including albumin and clotting factors. Synthesis of non-essential acids. Detoxification of metabolic waste products. Storage: Glycogen, vitamins, iron

Major function of liver : 

Major function of liver Intermediary metabolism Detoxification of various drug and toxins Secretion: Synthesis and secretion of bile.

Structure : 

Structure Glisson’s capsule Thickned at porta hepatis Send trabeculae into interior dividing the parenchyma in to complete lobules Portal tract or portal spcae or portal canal

Hepatocytes : 

Hepatocytes Large polyhedral cells Nuclei : Round with peripherally dispersed chromatin and prominent nucleoli. Vary greatly in size More than half of the hepatocytes contain twice the normal complement of choromose within a single nucleus and some contain four or even eight time Binucleted cells are common.

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Cytoplasm Eosinophilic and conatin abundant motichondria. Organelle like rER ,sER and golgicomplex Lipofusion Space of disse bile canaliculi

Portal tract : 

Portal tract Three main structure Terminal portal venule Largest terminal branch of hepatic portal vein. Thin walled Endothelial cells Hepatic artery Small Thick wall Bile ductules Lymphatics

Biliary tree : 

Biliary tree

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Bile canaliculus With in each plate of hepatocytes the canaliculi form a regular hexagonal network in the plane of the plate

Lobules of liver : 

Lobules of liver

Hepatic lobule : 

Hepatic lobule Hexagonal in shape Structural unit of liver. Terminal hepatic venule(central vein) Portal tract: at angle of heaxgone Portal triad: Connective tissue Portal venule Heatic arteriole Small heaptic ductule.

Hepatic lobule : 

Hepatic lobule Hepatocytes Main structural and functional components. Hepatic plate : One cell thick plates Radiating from central vein towards the peripheral of lobe. Branch and anastomose freely

Hepatic lobule: Hepatic sinusoids : 

Hepatic lobule: Hepatic sinusoids The irregular space between hepatic plates. Lining cells: Endothelial cells Flat darkly stain nuclei Thin fenestrated cytoplasm Kupffer cell Scattered among the endothelial cells Large plump phagocytic cells Ovoid nuclei Stellate cells, Ito cells or hepatic lipocytes.

Hepatic lobule: Hepatic sinusoids : 

Hepatic lobule: Hepatic sinusoids Space of Disse Irrigated by mixed blood Absorbed nutritive material and O2

Hepatic Acinar : 

Hepatic Acinar Functional unit of liver which is irrigated by the terminal distributing branches of portal vein and hepatic artery. Diamond shaped Three zone: 1, 2 and 3

Circulation of blood : 

Circulation of blood

Portal lobule : 

Portal lobule Functional unit of liver A part of the liver parenchyma that drains bile into the hepatic ductule present at portal triad. Triangular in shape Imaginary lines connecting the central veins of three adjacent live lobules with the portal triad at center.

Hepatic Acinar : 

Hepatic Acinar

Gall bladder : 

Gall bladder

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Muscular sac situated on the visceral surface of liver in the fossa for gall bladder. Concentrates bile by absorbing water and store the same. Capacity : 100 ml Cholecystokinin

Structure : 

Structure Mucosa Epithelium: simple columnar with microvilli Lamina propia Thrown into small fold when it is empty Muscularis mucosa and Submucosa :absent

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Musculari externa Arranged in three layer but do not form distinct layers. Serosa / Adventitia Depend upon the area Serosa : thick collagenous coat conveying blood and lymphatic vessels and

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Pancreas : 


Slide 31: 

An exocrine gland as well as an endocrine gland. Extended from concavity of duodenum on right to the spleen on the left in the posterior abdominal wall retroperitoneally.

Structure : Exocrine part : 

Structure : Exocrine part Serous acini arranged into many lobules. Interlobular septae of connective tissue which carry neurovascular structures and ducts.

Structure : Exocrine part : 

Structure : Exocrine part Serous acinus: Pyramidal serous cells Small lumen Darkly stain at base Lightly stain at apex and contain zymogen granules. Centroacinar cells

Duct : 


Structure : Endocrine part : 

Structure : Endocrine part Islets of Langerhans , Pale staining spherical bodies among the serous acini. More in tail region. 1 to 2 million islet Branching codes of endocrine cells ,supported by reticular fibres. Rich network of capillaries

Structure : cells of endocrine part : 

Structure : cells of endocrine part Alpha cells Form 20 % of total population. Large cells with eosinophilic granules. Found mainly at periphery of islet Secret glucagon

Structure : cells of endocrine part : 

Structure : cells of endocrine part Beta cells Form 70% of total population Small cells with basophilic granules Found mostly in centre. Secrete insuline

Structure : cells of endocrine part : 

Structure : cells of endocrine part Delta cells Form 5% of total population Secerte : somatostatin F cells Secrete pancreatic polypeptide which inhibit pancreatic secretion.

Applied : 

Applied Diabetes mellitus Type I insulin depended Type II non- insulin depended Pancreatic cancer

Conculsion : 


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