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Pancreas - Anatomy & Physiology (view source)
Revision as of 18:14, 10 December 2010
, 18:14, 10 December 2010no edit summary
Blind ending lymphatic vessels drain into larger lymphatic vessels that follow the course of the blood vessels in the connective tissue. Lymph drains into the '''pancreaticoduodenal''' lymph nodes. It then drains into the coeliac centre, which surrounds the coeliac artery.
Blind ending lymphatic vessels drain into larger lymphatic vessels that follow the course of the blood vessels in the connective tissue. Lymph drains into the '''pancreaticoduodenal''' lymph nodes. It then drains into the coeliac centre, which surrounds the coeliac artery.
==Histology==
===Exocrine===
[[Image:Islet and acini.jpg|thumb|right|150px|Acini and islet of Langerhans - © RVC 2008]]
*Consists of acini, which resemble bunches of grapes.
*Each acinus consists of a single layer of 40 - 50 pyramidal epithelial cells surrounding a lumen.
*The epithelial cells produce the secretion (pancreatic juice) containing enzymes, ions and water.
**Cells become wider during active secretion.
*The base of the acinar cells are strongly basophilic owing to the presence of endoplasmic reticulum where there is a high concentraion of RNA. This part of the cell therefore stains darker with haematoxylin and eosin.
*The apex of the cells is abundant with secretory granules containing the zymogen precursors of the pancreatic enzymes.
**The number of secretory granules increases after fasting and decreases after a meal.
*The lumen of the acini drain into the intercalated duct.
**Intercalated ducts converge to make larger interlobular ducts, which in turn converge to make interlobar ducts.
***Interlobar ducts are found in the connective tissue septa between lobules.
***Interlobar ducts join to form either the pancreatic or the accessory duct.
****These ducts drain into the [[Duodenum - Anatomy & Physiology|duodenum]].
****In some cases the pancreatic duct unites with the bile duct, and bile and pancreatic juice enter the [[Duodenum - Anatomy & Physiology|duodenum]] together.
===Endocrine===
[[Image:Islet cell types.jpg|thumb|right|150px|Islet of Langerhans - © RVC 2008]]
*Islets of Langerhans are embedded in the exocrine tissue.
*Each islet is composed of 2 - 3 thousand epithelial cells.
*Epithelial cells are arranged in a compact structure that is pervaded by a capillary network.
*A thin layer of reticular fibres seperates the islets from surrounding exocrine tissue.
*There are ''four'' different cell types within the islets of Langerhans that each produce different hormones.
**α cells produce glucagon. Typically located at the periphery of the islet. Not present in all islets.
**β cells produce insulin. The predominant cell type, located in the centre of the islet and contributing to 70% of all cells.
**δ cells produce somatostatin. Low numbers in all islets.
**F cells produce pancreatic polypeptide and are few in number, and may be present in the exocrine tissue also.
==Species Differences==
==Species Differences==