Page 647 - Atlas of Histology with Functional Correlations

Digestive System Part IV: Accessory Digestive

Organs

LIVER

Located outside the digestive tube in strategic position
All absorbed nutrients pass through liver via portal vein and hepatic
sinusoids

Has dual blood supply: portal vein and hepatic artery
Is organized into repeating liver lobules, with central vein in the center of
lobule
Plates of liver cells (hepatocytes) radiate to lobule periphery from central
vein

Portal vein, hepatic artery, and bile duct in lobule periphery are portal areas
Venous and arterial blood mix in sinusoids and flow toward central vein
Hepatic sinusoids lined with discontinuous and fenestrated endothelium

Substances in blood contact hepatocytes via subendothelial perisinusoidal
space of Disse
Phagocytic Kupffer cells and fat-storing hepatic stellate (Ito) cells are
associated with sinusoids
In liver damage, hepatic stellate (Ito) cells can differentiate into

myofibroblasts and produce connective tissue matrix
Performs more functions than any other organ
In fetus, it is the site for hematopoiesis or blood cell formation

Individual hepatocytes perform both exocrine and endocrine functions

Exocrine Functions

Hepatocytes secrete bile into tiny channels, the bile canaliculi, which merge

with canals of Hering
From the canal of Hering, bile flows toward bile ducts in portal areas in
opposite direction to blood
Bile is stored in gallbladder, where water is removed and bile is concentrated
Hormone cholecystokinin regulates the release of bile from liver and

646