Comparative Anatomy of the Liver and Pancreas PDF

DIGESTIVE SYSTEM COMPARATIVE ANATOMY OF THE LIVER AND PANCREAS DR ÍLKNUR AKTAN SENIOR LECTURER IN VETERINARY ANATOMY [email protected] Learning Objectives 01 02 03 04 05 06...

DIGESTIVE SYSTEM COMPARATIVE ANATOMY OF THE LIVER AND PANCREAS DR ÍLKNUR AKTAN SENIOR LECTURER IN VETERINARY ANATOMY [email protected] Learning Objectives 01 02 03 04 05 06 07 Describe the Describe the lobul Identify the Describe the Describe the type Describe the Describe the topography of the ation of the liver isolated liver and microscopic of cells within the function and the blood supply and liver and and pancreas in the pancreas of structure of the associated ducts of the liver venous drainage pancreas in the the domestic each of the associated organs and the pancreas of the liver and domestic species species domestic species organs within the the pancreas digestive system #uniofsurrey 2 XERTE EXERCISE TO BE COMPLETED https://xerte.surrey.ac.uk/play_1239 LIVER FUNCTIONS Detoxification and excretion (waste products) Secretion (Bile) Storage (lipids, vitamins A and B, glycogen) Synthesis (Albumin, clotting factors, globulins) Protein, carbohydrate and lipid metabolism Immune function (Kupffer cells) https://www.hopkinsmedicine.org/health/conditions-and-diseases/liver-anatomy-and-functions LO: Describe the function and the ducts of the liver and the pancreas S P E C I E S C O M PA R I S O N The largest gland in the abdominal cavity, caudal to the diaphragm Bulk lies to the right in all species and in ruminants entirely moved to the right Gall bladder between the right medial and quadrate lobe Some species have no gallbladder in the fossa (horses, rats) 5 Lo: Describe the topography of the liver and pancreas in the domestic species Dyce, 4th ed.  SURFACES OF THE LIVER Strongly convex surface towards the diaphragm (Parietal surface or diaphragmatic surface) Concave towards viscera (lies against and impressed by stomach, duodenum, etc.) hence visceral surface The visceral surface is marked by the porta of the liver  P O R TA O F T H E L I V E R The visceral surface is marked by the porta of the liver (bile duct, portal vein, and hepatic vessels enter and leave) Porta in Latin is gate Also known as hilar region of the liver 7 https://todaysveterinarypractice.com/imaging-essentials-small-animal-abdominal- ultrasonography-liver-gallbladder-part-1/ TOPOGRAPHY OF THE LIVER Located cranial part of the abdomen Cranial to liver is diaphragm Caudal to liver is the stomach, intestinal mass, and right kidney The right kidney makes contact with liver Adopts to the form of adjacent organs (e.g. renal impression of the caudate lobe) LO: Describe the topography of the liver and pancreas in 8 the domestic species LIVER LOBES Lobes Dog Pigs Ruminants Horse Rabbit Left Lobe + + + + + Left lateral + + _ + - lobe Left medial + + _ + - lobe Quadrate + + + + + lobe Right Lobe + + + + + Right lateral + + _ - - lobe Left medial + + _ - - lobe Caudate + + + + + lobe Caudate + + + + + process Papillary + - + _ + process LO: Describe the lobulation of the liver and pancreas in the domestic species DOG Liver is related on the left to the stomach (spleen); and on the right to the pancreas, kidney, and duodenum; and ventrally to the greater omentum Liver reaches the umbilical region on the ventral abdominal wall Its most caudal part covers the cranial extremity of the right kidney and reaches the 13th thoracic vertebra Extends slightly beyond the costal arch ventrally (more so in pups and in congestive heart failure) Liver biopsy-puncture caudal to the xiphoid process 10 Dyce et a. 4th ed. HORSE Lies completely within ribcage Located obliquely across the diaphragm with the left lobe ventral and right lobe dorsal Caudal margin reaches the 15th ICS Liver biopsy-12th ICS: on a line between the tuber coxae and point of the shoulder (right-hand-side) Liver biopsy-8th ICS: at the level of deltoid tuberosity of the humerus 11 Dyce et a. 4th ed.  RABBIT The liver has five lobes with a deep cleft dividing it into right and left lobes Ultrasound-guided biopsy can be taken ventrally from any lobe Caudate lobe has a narrow attachment to the porta region of the liver and could be a site of liver torsion Gallbladder present https://www.vetlexicon.com/lapis/surgery-soft-tissue/articles/liver-biopsy/ COW Liver reaches dorsally as far as the last rib Liver biopsy site 10th ICS: ¼ the of the length of the rib Gall bladder also rests 10th ICS Note the left lobe of the liver here (1) 13 König and Liebisch: Veterinary Anatomy of Domestic Animals 4th edition. L I V E R AT TA C H M E N T S Liver is covered by serosa (visceral peritoneum) overlying thin connective tissue capsule (tunica fibrosa-especially strong in Pigs) Some peritoneal folds have no supportive function but carry blood vessels, nerves and lymphatics Falciform ligament- between liver and diaphragm and the ventral abdominal wall Round ligament -fibrous strand in the free edge of the falciform ligament (umbilical vein remnant) Lesser omentum (Hepatoduodenal and Hepatogastric ligament) https://veteriankey.com/liver-and-biliary-system/ PERITONEAL FOLDS AND LIGAMENTS Peritoneal folds serve more to fix organs in position than as channels for blood vessels. These are called ligaments: -supportive function- attach liver firmly Coronary ligament- surround the caudal vena cava-attaches liver to the central tendon of the diaphragm Triangular ligaments extend between the dorsal part of the liver on each side of the diaphragm Right and left triangular and coronary ligaments that pass to the diaphragm from the parietal surface have fibrous cores https://veteriankey.com/liver-and-biliary-system/ D U A L B L O O D S U P P LY Hepatic portal vein - Large vein carrying nutrient rich (functional) blood from the unpaired organs into the liver -Supplying 60-70% of the blood flow Hepatic artery -Fresh oxygenated (nutritional) blood https://todaysveterinarypractice.com/soft-tissue-surgery/surgical-management-of-canine-liver-masses/ D U A L B L O O D S U P P LY The hepatic portal vein receives the venous blood form all unpaired abdominal organs (stomach, pancreas, spleen and intestines) Blood from the portal vein and hepatic artery branches mixes within the hepatic sinusoids before collecting in central veins These central veins merge and eventually form hepatic veins that drain into the abdominal portion of the caudal vena cava LO: Describe the blood supply and venous drainage of the liver and the pancreas https://veteriankey.com/hepatic-vascular-anomalies/ I N N E R VAT I O N Liver is innervated both sympathetic and parasympathetic nerves It receives fibers from the vagal trunk and sympathetic axons from celiac plexus/ganglion Vagal axons reach the abdomen by passing through the diaphragm with the oesophagus LO: Describe the blood supply and venous drainage of the liver and the pancreas H E PAT I C L O B U L E The basic structure of the liver is the hepatic lobule-hexagon shaped At each corner - an arteriole (from hepatic a.); a venule (from portal vein) and a small bile duct form the bile duct These three structures are commonly referred to as portal triad Each portal triad may provide blood to the several adjacent hepatic lobules LO: Describe the blood supply and venous drainage of the liver and the pancreas H E PAT I C L O B U L E Portal triad (or portal tract) contains three major structures: portal vein (PV), hepatic artery (HA), and bile duct (BD) LO: Describe the microscopic structure of the associated Dyce; 4th ed. organs within the digestive system H E PAT I C L O B U L E Arteriole and venule empty their blood into the spongy liver lobule Blood capillary beds that run between portal triad and central vein Capillary beds are lined by fenestrated, leaky endothelium known as liver sinusoids Blood flowing into the lobule is drained out via the central vein LO: Describe the microscopic structure of the associated organs within the digestive system BILE AND BILE DUCT Bile is produced by the sheets of hepatocytes Discharged into bile canaliculi Canaliculi unite to form the interlobular ducts -lobular ducts Hepatic ducts-cystic duct and the bile duct LO: Describe the microscopic structure of the associated organs within the digestive system PA N C R E A S The dorsal part of the abdominal cavity, often abuts the stomach and liver Small lobulated gland with two lobes joined by the body which is in contact with the pylorus Right lobe (7) is within mesoduodenum next to DD Left lobe (5) lies in the deep leaf of the greater omentum Coeliac and cranial mesenteric a. branches supply blood Dyce; 4th ed. PA N C R E AT I C D U C T S The pancreatic duct (greater) opens into the duodenum together or just beside the bile duct Accessory pancreatic duct (lesser) opens on the opposite In some species only one duct commonly Survives (sheep, pig) De Lahunta 7th ed. PA N C R E AT I C A N D B I L E D U C T S Horse- Bile and pancreatic ducts open at the first bend of the duodenal sigmoid flexure Dog-common bile duct enters the duodenum at the major duodenal papilla adjacent to, the pancreatic duct Cat-common bile duct and the pancreatic duct conjoin just before they enter into the major duodenal papilla Duct Horse Dog Cat Pig Sheep Cow Pancreatic + + (-) - - + - (+) Accessory + + + + - + Dyce; 4th ed. SUPPORTIVE READING Textbook of Veterinary Anatomy, Fourth edition, Dyce, Sack and Wensing Anatomy and Physiology of Farm Animals, seventh edition, Frandson, Wilke and Fails König and Liebich: Veterinary Anatomy of Domestic Animals 4th edition. 26