Liver 1 PDF - Functional Anatomy & Blood Supply
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University of Liverpool
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This document provides a detailed overview of the liver's functional anatomy, blood supply, and various functions, such as detoxification, bile production, and erythrocyte breakdown.
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Liver 1 LO1- Describe the functional anatomy of the liver Gross Anatomy In dome of diaphragm in abdominal cavity. 4 main lobes= Left, quadrate, right & caudate. In dog/cat/pig, L &R lobes have medial & lateral parts. Caudate lobe has caudate & papillary processes....
Liver 1 LO1- Describe the functional anatomy of the liver Gross Anatomy In dome of diaphragm in abdominal cavity. 4 main lobes= Left, quadrate, right & caudate. In dog/cat/pig, L &R lobes have medial & lateral parts. Caudate lobe has caudate & papillary processes. Lobes allow movement of liver due to diaphragm. Gall bladder= in carnivores/ruminants/pigs/mice, not in horses/rats (still produce bile but don’t store it). Histology CT capsule surrounds liver= extends into liver as highly branched septae, which delineate structural units of liver= hepatic lobule. Hepatocytes= chief functional cells, absorb molecules from space of disuse across sinusoidal membrane. Bile canaliculuc= dilates intercellular space between cells= bile secreted across cancalicular membrane. Billary system Bile from liver to duodenal lumen. Secrete biles across hepatocytes membrane into canaliculi then into small bile ducts= ductules which anastomoses into larger ducts, which coaleasce to form hepatic bile ducts. Bile duct enters duodenum at sphincter of oddi. Bile move between gallbladder & bile duct via cycstic duct. LO2- Describe the blood supply of the liver Blood supply Hepatic portal vein (75% blood entering), Hepatic artery (25% blood entering). Sinusoids (venous/arterial blood mix as flow into sinusoids). Central veins (sinusoids empty into central veins) Hepatic vein (central veins coalesce into hepatic veins). Caudal vena cava (hepatic veins empty into this). Hepatic Lobule Hexagonal shape. Lobules made of plates of hepatocytes which radiate out from central vein. Between lobules are portal ducts/triads= bile duct, hepatic artery, hepatic portal vein. Hepatic Acinus Functional unit of liver. Divided into zones= depends on distance from arterial blood supply. Zone 1 cells= closest to artery= best O2 supply. Zone 3 cells= furthest from artery= poorest O2 supply. Sinusoids Vascular channels. Lined by fenestrated endothelial cells. Surrounded by layers of endothelial cells. Macrophages/kupffer (unique to liver) cells patrol them. Blood flow form portal vein/artery through sinusoids to central vein. LO3- Summarise the main functions of the liver Functions of liver Detoxification of waste, xenobiotics, drugs. Synthesises cholesterol & bile acids. Synthesise plasma proteins. Breakdown RBCs/erythrocytes. Carb/lipid/AA metabolism. Remove bacteria= kupffer cells. Produce clotting factors. Store glycogen/iron/copper/vitamins. Liver metabolism Carbs metabolism= glycogenesis, glycogenolysis, glucaneogenesis. Lipid metabolism= oxidation of Fas & ketone body formation, cholesterol, phospholipids & bile acid synthesis. Protein metabolism Deamination & transamination of AAs. Synthesis of non-essential AAs. LO4- Describe the role of the liver in detoxification & clearance Detoxification & clearance Role in purification, transformation & clearance= substances from GI organs pass though liver via hepatic portal vein. Removes harmful substances from blood. Converts drugs/toxins into less toxic compounds. Hepatocytes microsomes contain non-specific enzymes system to oxidise substrates via co-enzyme cytochrome P450, followed by further degradation= conjugated with water soluble compounds & exerted in bile. Drugs/Pharmaceuticals= modified/degraded in liver, conjugates/modified for excretion in urine/bile. Toxins= detoxifies chemical agents/poisons, acute/chronic poisoning (phytotoxins/heavy metals). Endogenous metabolites- ammonia converted to urea & exerted as urine, hormones inactivated by liver, harm breakdown into bilirubin & exerted in bile. Examples of plant toxins Digitalis= from digitalis purpurea (foxglove), cardiac glycoside. Alfatoxin= from aspergillus fungal growth on damp grain/soybeans. Phylloerythrin= metabolite of cholorophyll causes photosensitisation in sheep. LO5- Describe the role of the liver in the break down of erythrocytes & the excretion of bile pigments Degradation of RBCs RBCs removed by macrophages in spleen/liver. To yield beam from haemoglobin. Harm converted to bile pigments, 1. Haem to biliverdin (green) in macrophages. 2. Biliverdin to bilirubin (yellow). 3. Bilirubin goes to liver in blood bound to albumin. 4. Bilirubin conjugates with glucoronic acid in liver. Excretion of bile pigments No part in digestion= waste route for haem. Conjugates bilirubin excreted into bile. Gut bilirubin acted on by intestinal bacteria= remove glucoronic acid, metabolise bilirubin to sterocoblin (brown)= gives faeces colour.