Functional Histology of the Liver Flashcards Preview

DEMS: Unit 1 > Functional Histology of the Liver > Flashcards

Flashcards in Functional Histology of the Liver Deck (11):
1

Blood flow through liver

  • major blood supply = hepatic portal vein (70-75%)
    • minor = hepatic artery (25-30%) = branch from celiac trunks
  • hepatic veins drain liver ==> inferior vena cava
    • vessel enter and leave @ "porta hepatis"
  1. hepatic portal vein + hepatic artery ==> interlobular  vessels 

  2. branching vessels of interlobular vessels ==> sinusoids ==> hepatocytes ==> central vein

2

Lobules of liver

  • liver lobules = smallest individual functional units w/in liver
  • classical lobule
  • portal lobule
  • acinar lobule

3

Characteristics of classic lobule

  • ~hexagonal-shaped arrangement
  • hepatocytes arranged radially around a central vein
  • interlobular vessels (located @ "vertices" of lobule) carry incoming blood from:
    • hepatic portal vein (deoxy)
    • hepatic artery (oxy)
  • bile ducts + space of Mall (lymphatic) also @ "vertices
    • bile secretion is separate via bile canaliculi

4

Characteristics of portal lobule

  • "portal lobule" = separate way of classifying same basic liver structure
  • portal lobule = ~triangular shape between three central veins
    • = zone of tissue around a biel duct into which a group of bile canaliculi feed
    • = basic bile secretory fxnl unit

 

5

Characteristics of acinar lobule

  • another structural-fxnl definition
  • "short axis" = between two portal triads
  • "long axis" = between two central veins
  • liver tissue in terms of blood delivery
  • 3 "zones"

6

Hepatocytes: structure/arrangement

  • polyhedral in shape
  • arranged in anastomosing plates or sheets with two sides facing the blood sinusoids (==> all hepatocytes exposed to plasma)
  • surface area of the hepatocyte plasma membrane increased ~5-10 fold through extensive microvilli

7

Fxns of hepatocytes

  • storage of glucose as glycogen
    • @ fasting: glycogen ==> glucose ==> blood
  • production of major blood proteins
    • albumin
    • clotting factors (e.g. prothrombin & fibrinogen)
  • production of lipoproteins
    • VLDL (mainly), LDL, IDL and HDL
  • produce bile
  • conjugation of toxins

8

Structure of bile canaliculi

  • formed via apposed grooves in adjacent hepatocytes
  • form circumferential belt around each hepatocyte ==> network of tubules running entirely within the hepatocyte plates

  • tight jxns = prevent leakage of bile

  • near portal triad: bile canaliculi ==> bile ductules ("canals of Hering")

9

Bile composition

  • bile salts (= cholate derivatives)
  • cholesterol, phospholipids, bilirubin glucoronides, and proteins + electrolytes
    • polymeric IgA

10

Pathway/structure from bile ducts to Gall Bladder

  • canals of Hering ==> interlobular bile ducts of portal triad
    • cubiodal epithelium ==> columnar as ducts fuse
  • @ porta hepatis ducts form lobar ducts ==> form common hepatic duct
    • microvilli transport electrolytes and water
  • common hepatic duct ==> cystic duct ==> gallbladder

11

Pathway/structure of common bile ==> duodenum

  • cystic duct + common hepatic duct ==> common bile duct

  • pancreatic duct ==> common bile duct

  • sphincters = 

    • sphincter of choledochus/Boyden = before entry of pancreatic duct

    • sphincter of Oddi = after entry of pancreatic duct