Liver and Gallbladder Lecture Notes PDF

Preview

Summary

Download Liver and Gallbladder Lecture Notes PDF

Description

Digestive System Liver and Gallbladder:  Liver o 1.4kg o Inferior to diaphragm o Occupies right hypochondriac and epigastric regions of abdominopelvic cavity o Anatomy  Covered by visceral peritoneum and irregular connective tissue  Two principal lobes  Right lobe o Large o Inferior quadrate lobe o Posterior caudate lobe  Left lobe o Small  Falciform ligament o Fold of peritoneum o Extends from undersurface of diaphragm between two principal lobes of liver to superior surface of liver  Helps to suspend liver in abdominal cavity o Free border  Ligamentum teres  Round ligament  Remnant of umbilical vein  Fibrous cord o Extends to umbilicus o Right and left coronary ligaments  Extensions of parietal peritoneum suspending liver and diaphragm o Histology  Lobules  Make up lobes  Six sided structure  Specialised epithelial cells o Hepatocytes  Arrangement  Irregular  Branching  Interconnected  Plates around central vein

Digestive System 



Sinusoids o Highly permeable capillaries o Fixed phagocytes  Stellate reticuloendothelial cells (Kuppfer) Bile o Secreted by hepatocytes o Enters bile canaliculi  Narrow intercellular canals emptying into bile ductules  Passing bile into bile ducts at periphery of lobules  Bile ducts emerge forming right and left hepatic ducts o Unite and exit liver as common hepatic duct o Common hepatic duct joins cystic duct from gallbladder to form common bile duct

o Blood supply  Receives blood from two sources  Hepatic artery o Oxygenated blood o Branches carry blood into liver sinusoids  Oxygen taken up by hepatocytes  Hapetic portal vein o Deoxygenated blood containing newly absorbed nutrients, drugs and microbes from GI tract  Hepatocyte products  Released into blood draining into central vein and eventually hepatic vein  Portal triad  Branches of hepatic portal vein, hepatic artery and bile duct  Located at corner of liver lobules

Digestive System

o Bile   

800-1000 mL secreted by hepatocytes a day pH 7.6-8.8 Consists of  Water  Bile salts  Cholesterol  Lecithin o Phospholipid  Bile pigments  Ions  Bilirubin  Pigment  Derived from phagocytosed red blood cells  Broken down in intestine o Stercobilin  Gives faeces brown colour  Bile salts o Sodium salts o Potassium salts o Bile acids  Emulsification  Breakdown of large lipid globules allowing for lipase to act more rapidly  Aid in absorption of lipids o Functions  Carbohydrate metabolism  Breakdown of glycogen  Conversion of amino acids and lactic acid into glucose  Conversion of glucose to glycogen  Lipid metabolism  Store of triglycerides  Break down fatty acids to ATP  Synthesise lipoproteins  Synthesise cholesterol  Make bile salts  Protein metabolism  Deaminate amino acids o Ammonia produced converted in to urea  Synthesise plasma proteins  Processing of drugs and hormones  Detoxify substances  Excrete drugs into bile  Chemically alter or excrete thyroid hormones and steroid hormones 

Excretion of bilirubin

Digestive System  



 

Synthesis if bile salts Storage  Glycogen  Vitamins o A o B12 o D o E o K  Minerals o Iron o Copper Phagocytosis  Red blood cells  White blood cells  Some bacteria  Done by Kupffer cells Activation of vitamin D Active form synthesised

Figure 1: Histology of Liver Lobule

Digestive System 

Gallbladder o Pear shaped sac o Located in depression of posterior surface of liver o 7-10 cm long o Hangs from anterior inferior margin of liver o Anatomy  Fundus  Projects inferiorly beyond inferior border of liver  Body  Central portion  Project superiorly  Neck  Tapered portion  Project superiorly o Histology  Mucosa  Simple columnar epithelium o Arranged in rugae  Absorption of water and ions  Lacks submucosa  Muscular coat  Smooth muscle fibres  Contraction ejects contents of gallbladder into cystic duct  Outer coat  Visceral peritoneum o Function  Store and concentrate bile produced by liver until needed in small intestine

Figure 2: The anatomy of the Liver and Gallbladder...