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24 Cards in this Set
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- Back
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Liver Functions
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**Regulates metabolism of carbs, lipids, and proteins; Secretion of bile and plasma proteins, drug and toxin Detoxification and excretion, & storage of glycogen, fat, iron, and vitamins
1) Detoxification: Zone 1- less subject to metabolite toxins vs. Zone 3- more vulnerable to toxins from metabolites b/c closer to central vein. 2) Regeneration: 3) Excretory Organ: bilirubin, cholesterol 4) Secretory Organ: bile (also recycles bile), IgA from GI tract plasma cells, glucose - glycogen stores, albumin & other plasma proteins, lipoproteins - VLDL 5) Conjugation of bilirubin to soluble product 6) Immune functions: Kupffer cells, IgA (from plasma cells in GALT in GI tract) - rides with bile to small intestine |
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Hepatocytes
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MORPHOLOGY:
-parenchymal cells organized into cellular plates -1 cell thick bordered by sinusoids - round nuclei and distinct nucleoli - abundant in granular and smooth ER (proliferates in response to fat soluble drugs to oxidize and inactivate the drugs) -peroxisomes with catalase: oxidative enzymes to rid toxins -lysosomes -GLYCOGEN GRANULES with some fat droplets: increase after meal and then drops during fasting b/c glucose released - Gap Junctions - electrotonic coupling: excitability of hepatocytes due to electric current FUNCTION: - process the blood that enters from GI and systemic circulation - produce bile and secrete it into canaliculi (formed by walls of adjacent hepatocytes & tight junctions) - regenerate for liver re-growth (growth is regulated depending on need by body) |
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Space of Disse
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separates hepatocytes from endothelial lining cells
FUNCTION: site of exchange from blood in sinusoids -> hepatocytes and from hepatoctyes -> blood CONTENTS: 1) RETICULATE FIBERS that support hepatocytes 2) Ito cells - Fat storing cells: release growth factors for regeneration 3) microvilli that increase SA for absorption |
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Hepatocyte Necrosis & Fibrosis
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- due to chronic liver damage or insults (hepatitis, alcohol consumption -> cirrhosis): CT overwhelms hepatocytes so blood flow to liver blocked
- blocked blood leads to PORTAL HYPERTENSION & LIVER DYSFUNCTION -> Jaundice |
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PROBLEMS WITH LIVER (ie. bile malabsorption, bilribubin, etc)
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Bile absorbed in ILEUM!!
1) buildup of Bilirubin -> can cross BBB feces unpigmented b/c usually bilirubin byproducts with excretion are brown 2) Diarrhea - bile excretion causes H2O to be excreted **bile secreted with fatty foods because CCK - green poop |
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Bile Canaliculi
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- enlargement in Extracellular Space between 2 hepatocytes & sealed by tight junctions (no intrinsic structure)
- seen in LM with PTAH or Silver stain that show tight junctions **VARIES FROM SILVER STAIN OF LIVER BECAUSE BILE CANALICULI ARE FORM CONTINUOUS POLYGONAL BRANCHING SYSTEM WITHIN LOBILE - NEATER SINGLE LOOKING LINES vs SILVER OF SINUSOIDS - MORE ALL AROUND AND CLUMPY: b/c stains space of disse and the hepatocytes - have microvilli and ATPase (what stains in enzyme cytochemistry) - converge into transitional canals - Canals of Hering -> Bile ducts (out of liver) |
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Bile Pathway OUT of liver
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- heaptocytes makes Bile -> bile canaliculi -> Canals of Hering (transitional canal - bile ductules) -> Bile Duct (in portal Triad) -> many bile ducts enter Hepatic Duct (exit liver) -> Common Bile duct (Cystic Duct from gall bladder also empties here) -> Pancreatic Duct & Bile Duct JOIN to SPHINCTER OF ODDI -> Duodenum
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Bile Duct
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- Simple Cuboidal epithelia --> High Columnar Epith. (in hepatic duct)
- part of portal canal (portal triad) |
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Portal Canal/Portal Triad
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1) lympatic tissue
2) portal vein - poorly oxygenated PORTAL blood from GI for detox 3) hepatic artery - oxygenated SYSTEMIC blood TO liver delivering nutritional support for metabolic activity of hepatocytes 4) Bile Duct **all bundled by DENSE CT; SEPARATED BY INTERLOBULAR CONNECTIVE TISSUE!!!!!!! |
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Kupffer cells
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WHAT:
- part of Mononuclear Macrophage System: MONOCYTES -> MACROPHAGES - Antigen Presenting Cells - part of Immune System WHERE: - lie in sinusoidal lumen FUNCTION: **-> MACROPHAGES! -Macrophages: part of innate (nonspecific) immunity and help initiate specific defence mech (cell-mediated immunity) -Innate Immunity: phagocyte (engulf and digest material) - Cell-mediated: stimulate lymphocytes to respond to pathogen - PHAGOCYTOSE particulate matter and decaying RBC's that pass through sinusoids: takes matter in TO PRESENT TO IMMUNE SYSTEM FOR DEGREDATION |
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Sinusoids
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WHAT: capillaries that carry the MIXED blood through hepatocytes
ARRANGEMENT: radially around central vein and in continuity with it's lumen --> Sinusoids EMPTY INTO CENTRAL VEIN FUNCTION: deliver nutrients, toxins, and pathogens absorbed in the intestine directly to hepatoctyes via Space of Disse (also exchange from hepatocytes to blood) COMPOSITION: 3 cell types lined with Space of Disse to separate endothelium from hepatocytes 1) ENDOTHELIAL CELLS - no basal lamina, Fenestrations/Discontinuous for MAX absorption; Flat nuclei 2) KUPFFER CELLS 3) ITO CELLS |
SINUSOIDS AND HEPATOCYTES LINED RADIALLY AROUND CENTRAL VEIN!!
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Blood Flow through Liver
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*Portal System (portal Vein) or Systemic System: (Hepatic Artery)
GI tract/Systemic-> portal vein/hepatic artery -> sinusoids -> central vein ->> many central veins empty into Sublobular Veins (thick CT, no accessory organs) -> many sublobular veins empty into Collecting Veins -> Hepatic vein -> Vena Cava |
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Portal Veins
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-carry blood from GI- contains material to be 'cleansed' by liver Kupffer cells
- part of Portal Triad: TERMINAL PORTAL VEINS: connect adjacent hepatocytes, center of HEPATIC ACINUS |
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Hepatic Acinus (Liver acinus)
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FUNCTION: flow of BLOOD between hepatocytes
MORPHOLOGY: - DIAMOND SHAPED: Portal triad on 2 corners connected by Terminal Portal vein and central Vein on other 2 corners - centered on terminal portal vein (blood flow between 2 portal triads) - 3 Zones |
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Portal Lobule:
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FUNCTION: flow of BILE through liver
-hepatocytes within triangle make BIle that enters bile duct in center MORPHOLOGY: TRIANGULAR: 3 corners are central veins and Center is Bile duct |
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Classic Lobule:
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hexagonal radiating arrangement of hepatocytes
- center is Central Vein - corners are Portal Triads NO FUNCTION! just STRUCTURAL LOBULE |
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Liver Organization:
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LOBULES: Basic Structural Unit of Liver that has plates of hepatocytes radiating from central vessel
- Composed of 100,000 classic lobules - LIVER IS THE LARGEST ORGAN IN THE BODY, BUT IT IS ONLY 1-2 CELLS THICK B/C FORMED BY HEPATIC PLATES (MADE UP OF A BUNCH OF HEPATOCYTES) THAT ARE SEPARATED BY SINUSOID |
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Functional Gradient of Liver Acinus
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ZONE 1: highest concentration of nutrients (o2) and highest concentration of toxins, lowest concentration of metabolite toxins; nearest to terminal portal Vein
ZONE 2 ZONE 3: lowest concentration of Toxins, highest concentration of metabolite toxins, Lowest concentration of Nutrients (low o2- vulnerable to apoxia); closest to central vein |
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Blood Vessels of the Liver: (ones we viewed in lab: not including collecting vein and hepatic vein)
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1) Sinusoids: radially arranged around central vein, one cell thick
NOT SURROUNDED BY CT: 2) Central Vein: epithelial lining directly in contact with hepatocytes SURROUNDED BY CT: 3) Sublobular Portal Veins: where central vein empties; no accompanying structures; THICK CT 4) Portal vein: thin walled, large vessel; part of Portal Triad/Canal 5) Hepatic Artery: thick wall, small vessel |
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Glisson's capsule:
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fibroelastic hepatic capsule that covers external surface of liver
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Gall Bladder
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FUNCTION:
- store bile from liver and concentrate it by absorbing H20 and electrolytes - releases bile in response to CCK that was released due to FA/peptides in duodenum MORPHOLOGY: MUCOSA: -1 epithelial cell type: narrow columnar --> no goblet, mucus cells w/ short microvilli!(distinguishes from small intestine) - lamina propria with Loose CT - NO MUSCULARIS MUCOSA/SUBMUCOSA - MUSCULARIS EXTERNA: interlacing loose smooth muscle - SEROSA: where it's free from Liver -ADVENTITIA: connects with liver wall (shares wall with liver) |
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Pancreas: Morphology - acinar cells and duct cells
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1) ENDOCRINE: islets of Langerhans - basal granules that secret into capillary plexus of the Islets
2) EXOCRINE: - ACINAR cells: eosinophilic apical granules - zymogen granules - Centroacinar cells: continuous from intercalated ducts - ALL INTERCALATED - no striated ducts --> intralobular ducts -> interlobular ducts -> pancreatic duct -> sphincter of Oddi (join with Common bile duct from liver & gall bladder)-> duodenum |
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Pancreas: Function
- ENDOCRINE - EXOCRINE (& affects by CCK & Secretin) |
ENDOCRINE
1) Beta cells - insulin 2) Alpha cells - glucagon 3) D cells: somatostatin EXOCRINE: Enzyme & Alkaline Fluid Release AFFECTED BY ENDOCRINE HORMONES!! ACINAR cells: FA/peptides -> AcH -> CCK: enzyme release AND bile secretion from gall bladder *INACTIVE FORMS: - Proteases: ie) Trypsinogen - activated by enterokinase from Enteroctyes in small intestine - Pro-Phospholipase A2 - Pro-Elastase *ACTIVE FORM -Glycolytic Enzymes: Amylase - breakdown Starch -Nucleotidases (RNA/DNA breakdown) - Pancreatic Lipase - Cholesterol breakdown: cholesterol esterase DUCT CELLS: low pH in duodenum -> VIP -> SECRETIN -> duct cell secretion of alkaline fluid, mediated by cAMP levels **secretin augments CCK stimulated enzyme rich secretions but ENZYME SECRETION IS INDEPENDENT OF ALKALINE FLUID RELEASE |
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BILE CANALICULI versus SINUSOIDS
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Bile Canaliculi: in BETWEEN 2 hepaotcytes - enlargement of extracellular space
-need close resolution to see vs. Sinusoids: can see from far resolution - MANY HEPATOCYTES AROUND IT! |
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