Histology 10b: Gregory Rodocker Nsu Class Taken: Spring 2009

Histology 10b

Gregory Rodocker NSU Class Taken: Spring 2009

Organs associated with the Digestive tract 

Three organs  Salivary glands  Liver  Gallbladder  Pancreas

Salivary Glands 

There are three extra-oral cavity sets of salivary glands  Parotid  Submandibular  Sublingual

Salivary Glands  

Serous cells in clusters that form circular structures called acini (sing. acinus) Mucous cells are arranged along the tubules  In the submandibular glands, the mucous cells are along the tubules and the serous cells cap the ends and are called serous demilunes

Salivary Glands 

Myoepithelial cells may function to contract and push saliva along but thought to function to maintain shape of duct system

Salivary Glands

Parotid Gland 

A branched acinar gland, mostly serous cells producing lots of enzymes

Salivary Glands 

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Parasympathetic control stimulates dilation of the capillary blood supply leading to copious watery secretion Sympathetic stimulation leads to constriction of the capillaries leading to small amounts of viscous saliva  Dry mouth when nervous

Submandibular Gland 

This gland containing a mixture of both mucous and serous cells

Sublingual Glands 

This gland is largely mucous producing cells

Pancreas 

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A mixed exocrine and endocrine gland producing enzymes and hormones Exocrine cells are arranged in acini whole the endocrine cells are in islets (islets of Langerhans)

Pancreas

Pancreatic secretions      

Trypsinogen 1, 2, and 3 Chymotrypsinogen Proelastases 1 and 2 Protease E Kallikreinogen Procarboxypeptidases A1, A2, B1 and B2

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Amylase Lipases Phospholipase Nucleases  Majority produced as inactive forms that are activated in the gut for the protection of the pancreas.

Pancreatic control 

Nervous and hormonal stimulation lead to pancreatic secretion  Secretin and cholecystokinin produced by Enteroendocrine Cells of the duodenum  Secretin – low enzyme, high bicarbonate  Cholecystokinin – high enzyme content  Parasympathetic stimulation

Liver 

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Second largest organ in body compared to skin Largest gland in the body Processes foodstuffs from digestion Detoxifies and eliminates toxins

Liver lobule 

Structural and functional unit of the liver is the lobule  Strings of hepatocytes radiating from a central vein that drains the lobule  At 3-6 locations around the lobule are portal spaces that each contain a venule, an arteriole and a duct (and a lymphatic vessel)

Specificity of hepatocytes by location in the lobule 

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Blood flow in the lobule is from periphery to center As a result, the hepatocytes called perilobular cells are exposed to a different milieu than the centrolobular hepatocytes Disease process and toxic damage may thus be sublobular rather than hololobular in nature.

Neonatal Hyperbilirubinemia

Underdeveloped Smooth ER in hepatocytes

alcoholic hepatitis

Giant cell hepatitis

Cirrhosis

Gallbladder 

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Role is to store and concentrate bile between food intake Bile is concentrated by pumping sodium out with chloride and water following

Gallbladder