The Liver and its Cardiovascular System, University of Portsmouth Presentation

Unit descriptor

• Review the structure, functions and biochemical processes associated with the following body systems; central nervous system; endocrine system and, gastro-intestinal system.
• Overview of conditions associated with the nervous, endocrine and gastrointestinal systems.

Introduction

• Liver
• Largest organ in the body

· 1.2-1.6 kg · 2-4% of bodyweight - Vital to life - no liver, no life - Babylonian hepatoscopy (350BC) · Sheep liver reading/Mirror of Heaven - Blood detoxification - Xenobiotic metabolism - Bile secretion - Biochemical homeostasis Dixit D A074 13 AOW 1981! ADA201 m x 1810 A2111 LA0/2:10 MOJUTA 7132 VODY8, 01219A 007 DA

British Liver Trust - Hugo

INJECTING DRUG USERS & HEPATITIS C.OR HUGO: THE MAN WITH THE TALKING LIVER HEY HUGO ! .. YOU'VE ONLY GOT ONE LIVER MATE, ME ! SPOTLIGHT ON THE LIVER I AM THE LARGEST ORGAN. I'M A FOOT LONG, WEIGH 3 POUNDS AND I'M VITAL TO YOUR BODY WITHOUT ME YOU'D BE ED ! PRIDE! YOU DRINK FIVE PINTS AND EAT A VINDALOO I SORT OUT THE GOODNESS AND BREAK DOWN THE CRAP. NOT ONLY THAT. I PERFORM OVER 100 OTHER FUNCTIONS. I AM A VITAL ORGAN Hugo

Introduction to Liver Function

• Serves as an interface between blood from GI tract and the bloodstream - 2 blood supplies . Portal venous system (GI tract) · Hepatic venous system (normal bloodstream) - Nutrients from GI tract processed/stored until needed - Bile production - exocrine secretion

Liver anatomy

• Structure - Located in right hypochondrium (behind ribs) - Top of abdominal cavity, beneath diaphragm - Enclosed by a thin connective tissue membrane - Glissons capsule - 2 main lobes · Left - smallest, Riedels lobe · Right - largest, quadrate and caudal lobes

Liver lobe anatomy

Liver op - bloodless resection Liver Spleen Gall- bladder Stomach Large intestine Small intestine adam.com

Hepatic blood supply

· 25% of resting cardiac output - 1.5L/min . Double blood supply - Hepatic artery - Hepatic portal vein · Both vessels enter liver at 'porta hepatis' · Blood drains from the liver via the hepatic vein

Hepatic portal system

Supplies about 80% of hepatic blood · Carries oxygen-poor, nutrient-rich blood from intestine, pancreas and spleen · Branches to form portal venules (in the triads) · Portal venules branch into smaller capillaries which empty into hepatic sinusoids Health Interactive @ 1999 WWW.RNCEUS.COM

Hepatic arterial system

· Supplies 20% of hepatic blood · Carries oxygenated blood from the aorta · Branches to form smaller arterioles and capillaries . Smallest vessels empty into sinuosoids hepatic vein hepatic artery gallbladder portal vein common bile duct

Sinuosoids

· Large spaces lined by specialist cells · Nutrient-rich portal blood and oxygen-rich arterial blood mix and surround hepatocytes and other cells. . Sinusoids conduct the blood centrally, converging into central vein - sublobular veins - hepatic vein - inferior vena cava

Sinuosoids H N

Scanning electron micrograph of Kupffer cell spanning the diameter liver sinusoid Note the fenestrations in the lining endothelial cells 11

Sinuosoids Structure

· Large spaces between hepatic plates · Walls lined by specialised cells - Endothelial cells - Kupffer cells - Ito cells · Structure allows hepatocytes to be in direct contact with blood/plasma · Offers protection from blood flow Liver acinus Sinusoid Central vein Septal branch Kupffer cell Hepatocyte 0 Bile canaliculus oh 0 0 Sinusoidal lumen Space of Disse Bile Kupffer canaliculi cell Hepatocyte 9 Hepatic artery branch 0 Portal vein branch Bile duct Stellate cell Endothelial cell with fenestrae 'Dendritic cell

Liver organisation

• Stroma - Lobule/acinus - Hepatic/portal triad - Central vein - Hepatocytes - Sinusoids - Canaliculi

Liver Lobule

connective tissue capsule = Glisson's capsule

Portal triad

· 3-6 triads per lobule · Corners between lobules · Surrounded by connective tissue . Also small lymphatics and autonomics Liver - Portal Triad Bile Ductule Hepatic Arteriole Portal Venule

Central vein

· Form the centre of the lobules . Blood drains from sinusoids · Radiating chords of hepatocytes called plates radial sinusoids draining into central vein

Liver lobule diagram

Liver Lobule Sinusoids 0 Bile Canaliculi 0 o O Bile Duct O 0 O O C O 0 0 O Branch Portal Vein Branch Hepatic Artery C Central Vein 0

Hepatocytes

· Predominant cell type in the liver - 60% liver cells - 80% liver volume - 250 billion - Large 20 - 30um - Unusual epithelia ·REF Mitochondria q Upids SER Tight Lysosomes (accluding] Bile- Junctions canalculus Golg SER Golo Desmosome SEŘ Microvill Glycogen Space of Disse Endothelium Reticular fibers Endothelial fenestration' Lumen of sinusoidal capillary APR CHLY

Sinusoid Endothelial Cells

Hepatocyte nisse space · 45% sinusoid cell volume · Flattened, elongated cells with cytoplasmic projections · Fenestrae - endothelial filter barrier - Blood/plasma in contact with hepatocytes · Space of Disse between Endo and Hepato · Endocytosis of cmpds - lipoproteins, glycoproteins

Kupffer cells

· 35% sinusoidal volume, inside sinusoids · Phagocytic cells - 80-90% of fixed macrophages · Pyramidal - star shaped - pseudopodia · Functions - phagocytosis, processing of antigens, synthesis and catabolismof lipids, clearing of erythrocytes, haemoglobin degradation, enzyme catabolism Supplemental Slide 124 Liver Kuppfer cells Kuppfer cell in sinusoid

Ito cells

. 20% cell volume - also called lipocytes, stellate cells or fat storing cells . Usually found within the Space of Disse (perisinusoidal space) · Characteristic large lipid vacuoles · Size and number dependent on nutritional status of the patient

Liver zones

• Zone 1 - Periportal cells, near portal triad - Blood with highest oxygen and nutrients - More resistant to damage
• Zone 2 - Intermediate zone

Pig Liver Anatomical Lobule

Pig Liver showing Anatomical Lobule & Portal Triad Central Vein Hepatocytes & Sinousoids Connective Tissue 3 2

Liver zones continued

• Zone 3 - Perivenular (pericentral/centrilobular), near central vein - Lowest oxygen content blood - More prone to damage - Abundant smooth ER - P450