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103 Cards in this Set

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  • Back
How much does the liver weigh?
Between 1200 - 1500 grams
What blood does the liver recieve?
Veinous blood from the
-Spleen
-Pancreas
-Intestine
2 major functions of the liver:
-Detoxify substances
-Absorb nutrients
What is the liver enveloped by?
Peritoneum
What type of epithelium is the peritoneum?
Simple squamous
What does the simple squamous epithelium cover?
The Dense irregular CT capsule called Glisson's capsule
Where is the glisson's capsule not loosely attached to the liver?
At the porta hepatis
What happens to it at the porta hepatis?
It enters the liver to form a conduit for the blood, lymph vessels, and bile ducts.
Does the liver have much connective tissue?
no
What is the bulk of the liver formed by?
Parenchymal cells
What are parenchymal cells?
Hepatocytes
What supplies blood to the liver? (3 vessels)
-Right hepatic artery
-Left hepatic artery
-Portal vein
How does blood leave the liver?
Via the hepatic veins
Where does bile leave the liver and go?
Via the bile duct to the gallbladder.
2 properties of the liver:
-Endocrine
-Exocrine
Where do the endocrine secretions come from and go?
-Directly from the hepatocytes
-Into the hepatic blood
What is the main exocrine function of the liver?
Secretion of bile
What are the 4 functional groups of hepatic components?
1. Connective tissue
2. Large vessels
3. Sinusoidal capillaries
4. Hepatocytes
What do the large vessels include?
Blood vessels
Lymphatic vessels
Nerves
Bile ducts
What are sinusoids?
Sinusoidal capillaries that line plates of hepatocytes
What is an important hormone that is sereted by hepatocytes?
Thyroxin
How does the liver function in metabolism?
-Maintains normal glucose levels in the blood by 1. Storing glycogen, 2. Releaseing it when needed, and 3. Making it from other noncarb sources/sugars
When hepatocytes break down glycogen via glycogenolysis, where do they release it into?
The space of Disse
What type of capillaries make up the sinusoidal capillaries between cords of hepatocytes?
Fenestrated
Do these fenestrated capillaries have a basement membrane separating them from the hepatocytes?
No; blood can freely wash over the hepatocytes as it flows in and out of the fenestrations.
What is the space between the endothelial cells of sinusoidal caps and the hepatocyte cords?
The space of disse
What does the space of disse contain?
Reticular fibers made of Type III collagen
What does the reticular network extend out from?
The central vein of each lobule
What other connective tissue is in liver lobules?
That's it - just the reticulin
What is the function of the Reticulin?
To support the hepatocytes and keep the sinusoids open
What cells make the reticulin? Where?
Ito cells, aka Stellate cells - in the space of disse
What is thickened and abnormally prominent reticulin between the hepatocytes and sinusoids a sign of?
Hepatic cirrhosis
What causes hepatic cirrhosis?
Hepatic necrosis
What is the hepatocyte's response to necrosis?
1. Collapse of hepatic lobule organization
2. Nodular regrowth
3. Fibrosis
What causes the fibrosis in hepatic cirrhosis?
Increased activity of the stellate cells, depositing more type I and III collagen.
How many major vessel systems are in the liver? What are they?
FIVE:
1. Hepatic artery
2. Hepatic portal vein
3. Central veins
4. Bile ducts
5. Lymphatic vessels
What does the hepatic artery carry?
Oxygenated blood from the arteries
What does the Hepatic portal vein carry?
Venous blood from the organs to the liver
What do central veins carry?
Blood away from the liver to the hepatic veins, to eventually dump into IVC
How does blood go from the huge hepatic artery, carrying the blood with RBC brkdown products, digested food, pancreatic enzymes, etc, to the sinusoids?
Via Arterial capillaries and inlet venules that branch off from it.
What blood flows into the sinusoids?
BOTH
-Portal vein (nutrient-rich)
-Hepatic artery (O2-rich)
What does a Portal Triad consist of?
-Branch of Hepatic artery
-Branch of Hepatic portal vein
-Bile duct
Where does the blood from the 2 arteries in the triad go?
Down the sinusoids, then dumps into the central vein.
What happens to central veins?
They join together to flow into the IVC
What 2 types of cells make up the sinusoids?
-Sinusoidal endothelial cells
-Kuppfer cells
What are Kupffer cells?
Specialized macrophages that possibly breakdown senescent RBCs
So where does exchange between blood and hepatocytes take place?
In the Space of Disse
On what sides of the hepatocyte are the Space of Disse?
On each of its 2 basal sides.
What special surface feature do hepatocytes have on their basal side?
Microvilli
What cells are found in this Space of disse?
Stellate/Ito cells
What are these Ito cells?
Adipocytes
Why are Ito cells important?
They store vitamin A! And make reticulin of course.
What are the functional units of the liver?
Lobules
In what directions do bile and blood flow?
Opposite
How is the classic lobule described?
-Hexagon
-6 portal triads at each point
-1 central vein
Why is it hard to see the classic lobule in humans?
Because our CT is not as thick as that in pigs
Where are the basal surfaces of hepatocytes?
Facing the sinusoid
Where are their apical surfaces?
Facing the bile ducts
Where are their lateral surfaces?
Facing adjacent hepatocytes
What are the cell structures and genetics of hepatocytes like?
-Rich in organelles
-Binucleate
-Tetraploid (4N)
What are the predominant organelles that reflect the high metabolic activity of hepatocytes?
-RER, Mitochondria
-Glycogen granules
-Lipid droplets
What would a "portal" lobule consist of?
A triangle:
-3 central veins
-1 portal triad at the middle
What is an "Acinus" functional unit?
A lozenge shaped unit, with 2 triads making up the short axis and 2 central veins making up the long axis.
So instead of blood flowing from the 6 edges toward the center, how does it flow in the acinus?
From the middle toward the 2 opposite ends
How does the way in which blood perfuses the acinus allow us to look at hepatocytes?
In terms of their order of encountering blood.
What are the 3 concentric zones of hepatocytes within the acinus?
Zone 1 - encounters first
Zone 2
Zone 3 - encounters last
Which cells are the last to die and first to regenerate if circulation is impaired?
The zone 1 cells - they encounter the best blood
Which cells are first to show ischemic necrosis and fat accumulation?
Zone 3 cells
Which cells are the last to respond to toxic substances and bile stasis?
Zone 3
So the principle functional cell of the liver is the:
hepatocyte
How many cells thick are the plates of hepatocytes that make up cords?
1-2
What are hepatocytes really?
Epithelial cells with 6 sides
Main exocrine function of the liver:
production of bile
What does bile consist of?
An isotonic solution of water and electrolytes
What causes jaundice?
Failure to remove bilirubin
What do bile acids come from?
Cholesterol metabolism
What side of hepatocytes does bile come out of?
The apical side
Where does it go?
Into bile canaliculi
Where are bile canaliculi?
Around hepatocytes
What do canaliculi join together to form?
Canals of herring - ductules
What are bile ducts made of?
Biliary epithelial cells
What type of epithelial cells?
Cuboidal
Where do the bile ductules drain into?
The bile ducts at the portal triad
Where do bile ducts drain?
Into the hepatic duct back at the portal entrypoint of the whole liver
How much bile does the human liver secrete daily?
1 liter
Where does bile go from the hepatic duct? Why?
To the gallbladder to be concentrated
What is formed when the hepatic duct joins the cystic duct?
The common bile duct
What joins with the common bile duct?
The pancreatic duct
What stimulates the gall bladder to contract and release concentrated bile into the duodenum?
CCK
What stimulates CCK release?
The presence of fat in the duodenum
What is the gallbladder like structurally? how much can it hold?
A muscular sac
-holds up to 100 mls per day
What does the lumen of the gallbladder feature?
Numerous deep mucosal folds with apical microvilli on simple columnar epithelial cells
what does the lumen of the gallbladder resemble?
The absorptive cells of the intestine
How does the gallbladder concentrate bile?
By actively absorbing water into its epithelial cells, then into a capillary network in its lamina
Do the mucosal folds of the gallbladder lumen go away when it is distended?
no
What is the most common disease associated with the gallbladder?
Cholethiasis - gallstones
What is treatment?
Removal of gallbladder
Can the LIVER regenerate?
yes - partial hepatectomy is a model for it
When liver lobes are dissected out of rodent livers, do they grow back?
No, but the remaining lobes enlarge to make up for the removed mass.
What types of liver cells regenerate?
All types
What regulates liver regeneration?
Both pos and neg signals
Can transplanted hepatocytes efficiently repopulate damaged livers?
Yes
What are oval cells?
A potential source of hepatic stem cells in the bone marrow