GI module 4 Flashcards
The functional unit of the liver is a hexagonal arrangement. Describe the parts of this.
- hexagonal hepatocytes and microvasculature
- central vein at center of hexagon
- At each corner is a portal triad
What does the microvasculature of the hepatocyte contain?
sinusoid and bile canaliculi
Name the parts of the portal triad
Terminal branch of the hepatic artery
Terminal branch of the portal vein
Terminal bile duct
Describe the pathway of bile
Bile canaliculi drain into terminal bile ducts
Terminal bile ducts drain into R/L hepatic ducts
R/L hepatic ducts merge to form common hepatic duct
Common hepatic “divides” into cystic (gallbladder) and common bile which merges with the pancreatic duct to drain into the duodenum
T/F liver has the ability to regenerate?
T
What are some of the signaling mechanisms that stimulate liver regeneration?
TGF, HGF, EGF
If 50-60% of the liver is damaged from 4 days of acetaminophen how long will it take for the liver to completely regenerate?
within 30 days.
What are the 2 afferent pathways to the liver and what percent do each supply?
Portal pathway (hepatic portal vein) 75% Arterial pathway (hepatic artery) 25%
What does the portal pathway primarily supply?
nutrients
What does the arterial pathway primarily supply?
O2
If there is congestion in the portal vein what levels will increase?
02
What structures make up the efferent pathway of the liver?
Central veins
Hepatic veins
Where do the central veins drain into?
hepatic veins
Where do the hepatic veins drain in to?
IVC
t/f the liver produces a large amount of lymph?
T
The hepatic portal vein receives blood from?
The GI tract, spleen and pancreas
What does the hepatic portal vein carry?
A large amount of nutrients from the GI tract, and a relatively small amount of O2
Where does the hepatic portal vein terminate?
Divides into R/L branches and further divides until it finally delivers blood to portal vein
What collateral veins are part of the hepatic portal anastomosis?
Gastroesophageal v.
Rectal v.
Paraumbilical v.
Portorenal v.
When congestion d/t cirrhosis is present what may also be seen on inspection?
Distention of the hepatic portal anastomosis veins
Where does the hepatic artery originate from?
The celiac trunk
Is blood flow from the hepatic artery impaired during cirrhosis?
NO.
What acts as a “capillary bed” for hepatocytes?
Sinusoid
What 2 vessels do the sinusoid receive blood from?
Terminal branches of hepatic portal veins, and artery
What works to expose hepatocytes to hepatic blood flow?
sinusoids
Where does the sinusoid drain into?
Central vein
Where are Kupffer cells located?
Surface of the endothelium
What do Kupffer cells function to do?
Phagocytic removal of immune complex
RBC degradation-remove damaged RBC’s
SERVES AS EARLY FRONT LIKE DEFENSE AGAINST LIVER DAMAGE
What structure allows nutrients/lipids to travel through the sinusoidal wall and flow to microvilli of hepatocyte?
Fenestrated endothelium
Where are the stellate cells located?
Space of Disse
What is the function of stellate cells?
Store vitamin A
Produce/secrete hepatic factors (liver regen)
What pathological relationship do stellate cells have?
Role in fibrosis!! If disrupted transforms into fibroblastic and myoblastic function
What are Pit cells aka?
Granular lymphocytes, or NK natural killer cells
Where are Pit cells located?
surface of endothelium
What is the function of Pit cells?
front like immune defense, attacks tumor/virus
Liver regen.
What organ produces the largest amount of lymph fluid in the body?
the liver
T/f approximately 10% of lymph fluid is produced in the liver?
F 20% (a huge number relatively)
What are the 2 regional zones of hepatocytes in the lobule?
periportal hepatocytes
Centrilobular hepatocytes
What is the major difference between periportal and centrilobular hepatocytes?
Perioportal are the “oldest kid” They get all the stuff-first to receive blood therefore are O2 and nutrient rich.
Centrilobular are not as exposed and are last to receive blood and have less O2.
Which lobular zone is more likely to be damaged by ischemia (or first to be damaged?)
centrilobular
What are the primary physiological roles of the liver?
Drug metabolism/biotransformation
Metabolism
Storage
endocrine
In what ways is the liver involved in carbohydrate metabolism?
Regulates blood glucose
Storage of glucose for future energy needs
Gluconeogenesis
What is the rate limiting step in gluconeogenesis?
The amount of substrate (NOT liver enzymes)
