{"id":4422471,"date":"2025-01-11T20:25:08","date_gmt":"2025-01-12T02:25:08","guid":{"rendered":"https:\/\/myendoconsult.com\/learn\/topics\/anatomy-of-the-pancreas\/"},"modified":"2025-01-12T13:29:36","modified_gmt":"2025-01-12T19:29:36","slug":"anatomy-of-the-pancreas","status":"publish","type":"oen_topic","link":"https:\/\/myendoconsult.com\/learn\/topics\/anatomy-of-the-pancreas\/","title":{"rendered":"Anatomy of the Pancreas"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">PANCREAS ANATOMY AND HISTOLOGY<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Gross Anatomy<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Location and Position<\/strong>\n<ul class=\"wp-block-list\">\n<li>Retroperitoneal organ, <strong>15\u201320 cm<\/strong> long, <strong>75\u2013100 g<\/strong> weight.<\/li>\n\n\n\n<li>Oblique position: from duodenum (right) to splenic hilum (left).<\/li>\n\n\n\n<li><strong>Four Regions<\/strong>: head, neck, body, tail.<\/li>\n\n\n\n<li><strong>Head<\/strong>: resides in C-loop of duodenum, anterior to vena cava, right renal artery, both renal veins.\n<ul class=\"wp-block-list\">\n<li>Uncinate process = posteromedial aspect, behind portal vein &amp; SMA\/SMV.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Neck<\/strong>: anterior to portal vein, at L1\u2013L2 level.<\/li>\n\n\n\n<li><strong>Body<\/strong>: extends anterior to aorta (origin of SMA).<\/li>\n\n\n\n<li><strong>Tail<\/strong>: left end, near spleen, anterior to left kidney, over splenic hilum.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Peritoneal Cover<\/strong>\n<ul class=\"wp-block-list\">\n<li>Anterior surface covered by peritoneum.<\/li>\n\n\n\n<li>Base of transverse mesocolon attaches to inferior margin of body\/tail.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"2400\" height=\"1950\" src=\"https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/Pancreas-Anatomy.png\" alt=\"\" class=\"wp-image-4422768\" srcset=\"https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/Pancreas-Anatomy.png 2400w, https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/Pancreas-Anatomy-300x244.png 300w, https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/Pancreas-Anatomy-768x624.png 768w, https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/Pancreas-Anatomy-1536x1248.png 1536w, https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/Pancreas-Anatomy-2048x1664.png 2048w\" sizes=\"auto, (max-width: 2400px) 100vw, 2400px\" \/><figcaption class=\"wp-element-caption\">location of the pancreas<\/figcaption><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Embryologic Origin<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Fusion of Ventral &amp; Dorsal Buds<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Ventral bud<\/strong> \u2192 duct of Wirsung (main pancreatic duct), becomes inferior portion of head + uncinate process.<\/li>\n\n\n\n<li><strong>Dorsal bud<\/strong> \u2192 duct of Santorini (accessory), becomes body &amp; tail.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Duct Anatomy<\/strong>\n<ul class=\"wp-block-list\">\n<li>Main duct (Wirsung) joins common bile duct \u2192 ampulla of Vater \u2192 empties into duodenum (2nd part).<\/li>\n\n\n\n<li><strong>Sphincter of Oddi<\/strong> controls flow of bile &amp; pancreatic juice at ampulla of Vater.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Blood Supply and Drainage<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Arteries<\/strong>\n<ul class=\"wp-block-list\">\n<li>Branches from <strong>celiac trunk<\/strong> (via splenic artery &amp; common hepatic\/gastroduodenal) and <strong>SMA<\/strong>.<\/li>\n\n\n\n<li><strong>Head &amp; Uncinate<\/strong>: gastroduodenal artery branches, SMA branches.<\/li>\n\n\n\n<li><strong>Body &amp; Tail<\/strong>: branches of splenic artery &amp; inferior pancreatic artery (from SMA) \u2192 form arterial arcades.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Veins<\/strong>\n<ul class=\"wp-block-list\">\n<li>Head region: anterior &amp; posterior venous arcs \u2192 drain to portal &amp; mesenteric veins.<\/li>\n\n\n\n<li>Body &amp; Tail: venous outflow \u2192 <strong>splenic vein<\/strong> \u2192 portal system.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Lymphatics<\/strong>\n<ul class=\"wp-block-list\">\n<li>Dense lymphatic network draining to local\/peripancreatic LNs.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Innervation<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Sympathetic &amp; Parasympathetic<\/strong>\n<ul class=\"wp-block-list\">\n<li>Innervate acinar (exocrine) cells, islet (endocrine) cells, vasculature.<\/li>\n\n\n\n<li><strong>Parasympathetic<\/strong> \u2192 stimulates secretions (endo &amp; exo).<\/li>\n\n\n\n<li><strong>Sympathetic<\/strong> \u2192 generally inhibitory.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Neurotransmitters &amp; Peptides<\/strong>\n<ul class=\"wp-block-list\">\n<li>Peptides\/ amines (somatostatin, galanin, VIP, CGRP) released by pancreatic nerves.<\/li>\n\n\n\n<li>Afferent sensory fibers \u2192 explain severe pain in pancreatitis.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Histologic Components<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Tissue Distribution<\/strong>\n<ul class=\"wp-block-list\">\n<li>~85% exocrine, 2% endocrine, 10% extracellular matrix, 3\u20134% vessels &amp; ducts.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Exocrine Portion<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Acinar cells<\/strong> in clusters\/lobules \u2192 secrete digestive enzymes into ducts \u2192 main pancreatic duct \u2192 duodenum.<\/li>\n\n\n\n<li>Acinar cells: abundant RER, apical zymogen granules.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Endocrine Portion (Islets of Langerhans)<\/strong>\n<ul class=\"wp-block-list\">\n<li>Scattered small clusters in the acini.<\/li>\n\n\n\n<li>3 main cell types:\n<ul class=\"wp-block-list\">\n<li><strong>\u03b2-cells<\/strong> (75%) \u2192 insulin<\/li>\n\n\n\n<li><strong>\u03b1-cells<\/strong> (20%) \u2192 glucagon<\/li>\n\n\n\n<li><strong>\u03b4-cells<\/strong> (5%) \u2192 somatostatin<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Other <a href=\"https:\/\/myendoconsult.com\/learn\/islet-cells-of-the-pancreas\/\" data-wpil-monitor-id=\"223\">islet cells<\/a>: \u03b42-cells (VIP), PP-cells (pancreatic polypeptide).<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"3000\" height=\"2100\" src=\"https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/pancreas-anatomy-histo.png\" alt=\"\" class=\"wp-image-4422765\" srcset=\"https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/pancreas-anatomy-histo.png 3000w, https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/pancreas-anatomy-histo-300x210.png 300w, https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/pancreas-anatomy-histo-768x538.png 768w, https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/pancreas-anatomy-histo-1536x1075.png 1536w, https:\/\/myendoconsult.com\/learn\/wp-content\/uploads\/pancreas-anatomy-histo-2048x1434.png 2048w\" sizes=\"auto, (max-width: 3000px) 100vw, 3000px\" \/><figcaption class=\"wp-element-caption\">Histology of the Pancreas<\/figcaption><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">EXOCRINE FUNCTIONS OF THE PANCREAS<\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Pancreatic Juice<\/strong>\n<ul class=\"wp-block-list\">\n<li>~1 L\/day, alkaline, isosmotic, rich in HCO\u2083\u207b &amp; proteins.<\/li>\n\n\n\n<li><strong>Functions<\/strong>: neutralize gastric acid in duodenum &amp; digest macronutrients.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Digestive Enzymes<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Amylase<\/strong>: degrades starch, glycogen \u2192 maltose, dextrins.<\/li>\n\n\n\n<li><strong>Proteases<\/strong> (secreted as proenzymes): trypsinogen (\u2192 trypsin by duodenal enterokinase), chymotrypsinogen, elastase, carboxypeptidases \u2192 degrade proteins to peptides\/amino acids.\n<ul class=\"wp-block-list\">\n<li>Pancreatic secretory trypsin inhibitor prevents autoproteolysis.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Lipolytic Enzymes<\/strong>: lipase, phospholipase A2, etc. \u2192 break down fats into FAs, glycerol, micelles.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Acinar Architecture<\/strong>\n<ul class=\"wp-block-list\">\n<li>~40 acinar cells\/acinus, plus <strong>centroacinar<\/strong> cells at center near duct origin \u2192 secrete electrolytes, bicarbonate.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Regulation of Secretion<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Basal rate<\/strong> ~2% of max; <strong>Meal-stimulated<\/strong> phases:\n<ul class=\"wp-block-list\">\n<li><strong>Cephalic (10%)<\/strong>: via sight\/smell of food, mediated by cholinergic input.<\/li>\n\n\n\n<li><strong>Gastric (10%)<\/strong>: distention \u2192 gastrin + vagal reflex \u2192 moderate enzyme\/bicarbonate secretion.<\/li>\n\n\n\n<li><strong>Intestinal (80%)<\/strong>: acid\/fat\/protein in duodenum \u2192 secretin (\u2191 HCO\u2083\u207b secretion), CCK (enzyme secretion), synergy for maximum output.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">NORMAL HISTOLOGY OF PANCREATIC ISLETS<\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Islet Distribution &amp; Size<\/strong>\n<ul class=\"wp-block-list\">\n<li>~1 million islets, mostly in <strong>tail<\/strong> region. Size 40\u2013300 \u00b5m.<\/li>\n\n\n\n<li>Each islet ~3000 cells; total islet mass ~1 g.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Cell Types &amp; Arrangement<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>\u03b2-cells<\/strong>: 75%, central in islet, produce insulin (Ponceau\/Gomori stain: bluish-purple granules).<\/li>\n\n\n\n<li><strong>\u03b1-cells<\/strong>: 20%, peripheral in islet, produce glucagon (stain pink\/red).<\/li>\n\n\n\n<li><strong>\u03b4-cells<\/strong>: 5%, smaller, produce somatostatin.<\/li>\n\n\n\n<li><strong>PP-cells<\/strong>: produce pancreatic polypeptide (mainly in head).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Insulin<\/strong>\n<ul class=\"wp-block-list\">\n<li>56\u2013AA peptide (two chains + disulfide bonds), discovered in 1920.<\/li>\n\n\n\n<li>Regulated by plasma glucose, neural signals, paracrine factors.<\/li>\n\n\n\n<li>Enhances glucose uptake, glycogen storage, protein synthesis; inhibits <a href=\"https:\/\/myendoconsult.com\/learn\/gluconeogenesis\/\" data-wpil-monitor-id=\"224\">gluconeogenesis<\/a>, lipolysis, ketogenesis.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Glucagon<\/strong>\n<ul class=\"wp-block-list\">\n<li>29\u2013AA single chain, antagonizes insulin, promotes hepatic glycogenolysis &amp; gluconeogenesis.<\/li>\n\n\n\n<li>Inhibited by high glucose, GLP-1, insulin, somatostatin.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Somatostatin<\/strong>\n<ul class=\"wp-block-list\">\n<li>14 or 28\u2013AA forms, generally inhibits hormone secretion (insulin, glucagon, GH, etc.).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Pancreatic Polypeptide (PP)<\/strong>\n<ul class=\"wp-block-list\">\n<li>36\u2013AA hormone, inhibits gallbladder contraction, bile &amp; pancreatic exocrine secretions; modulates insulin receptor.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Amylin (IAPP)<\/strong>\n<ul class=\"wp-block-list\">\n<li>37\u2013AA co-secreted w\/ insulin.<\/li>\n\n\n\n<li>Slows gastric emptying, inhibits digestive secretions, suppresses glucagon release.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>PANCREAS ANATOMY AND HISTOLOGY Gross Anatomy Embryologic Origin Blood Supply and Drainage Innervation Histologic Components EXOCRINE FUNCTIONS OF THE PANCREAS NORMAL HISTOLOGY OF PANCREATIC ISLETS<\/p>\n","protected":false},"featured_media":0,"template":"","oen_topic_chapter":[686],"class_list":["post-4422471","oen_topic","type-oen_topic","status-publish","hentry","oen_topic_chapter-the-pancreas","post-wrapper","thrv_wrapper"],"_links":{"self":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422471","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic"}],"about":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/types\/oen_topic"}],"version-history":[{"count":5,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422471\/revisions"}],"predecessor-version":[{"id":4422769,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422471\/revisions\/4422769"}],"wp:attachment":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/media?parent=4422471"}],"wp:term":[{"taxonomy":"oen_topic_chapter","embeddable":true,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic_chapter?post=4422471"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}