Discuss some basic functions of the liver
-The liver takes up digested nutrients such as carbohydrates, amino acids, lipids and vitamins.
-Stores and releases glucose, triglycerides and vitamins.
-Synthesizes numerous products which it releases to the blood stream, including albumin, clotting factors, serum proteins, cholesterol and phospholipids among others.
-Liver is also responsible for engulfing and destroying metabolites, drugs, foreign materials, bacteria, and worn out cells and proteins.
-The liver secretes ~750ml of bile/day
-Is a site of embryonic hematopoesis and delivers IgA to the gut via bile
What are the epithelial cells that form the parenchyma of the liver?
What are 3 distinguishing characteristics of a liver cell?
1. Has a central nucleus and can be binucleate. Usually has a prominent nucleolus.
2. May contain large quantities of glycogen and/or liver
3. microvilli that extend into the perisinusoidal space
True or False: Each hepatocyte performs all of the same functions all of the time?
False; while each hepatocyte is capable of all of the functions, the actual activity of individual cells is dependent on the position of the cell in the liver lobule and the physiological or pathological state of the animal.
How does the endothelial lining and hepatocyte microvilli participate in liver cell function?
The endothialial cells are fenestrated which will allow for the diffusion of plasma (not big enough for whole blood cell) through this layer. The microvilli increase the surface area of the hepatocyte and also function to slow down movement and allow phagocytocis or endocytosis to happen.
Hepatocytes are lined by _____ cells.
______ cells are stellate shaped cells that togther with endothelial cells line the sinusoids.
What structures found on the surface of Kupffer cells that aid in phagocytocis.
Fc and C' receptors which activate the compliment pathway for endocytocis/phagocytosis
Where are kupffer cells located?
in the liver sinusoids
True or False:
Hepatocytes and Kupffer cells have receptors for asialoglycoproteins (ASGP-R), mannose 6-PO4 (MP-R) and low density lipoproteins (LDL-R)
What type of liver cell is known as a fixed macrophage of the sinusoids?
Name 4 functions of Kupffer cells.
1. Phagocytosis of immune and non-immune complexes as well as bacteria.
2. Bind hemoglobin and break it down
3. RBC degredation (take over from spleen)
4. Antigen processing and presentation
What cell type often accompanies Kupffer cells in the sunusoids?
Fat-storing cells (Ito)
What is a characteristic feature and main function of the Ito cells?
Ito cells or fat-storing cells contain lipid droplets. These cells will rapidly take up Vitamin A and store it.
What is a main characteristic of endothelial cells of the liver?
Endothelial cells are fenestrated and have no associated pericytes. Basal lamina is usually indistict but type IV collagen and laminin.
What two cell types make up the most volume in the liver?
Kupffer cells- 40%
Endothelial cell - 48%
fat storing cells - 13%
___ is a reticular framework of cells associated with liver structure.
True or False: Liver normally has a lot of connective tissue associated with it?
False: The stroma is a reticular framework that has little connective tissue except in pigs.
What's the difference between a lobe and a lobule?
A lobe, which is grossly visible, is made up of lots of lobules. The lobules are only grossly visible in the pig. The lobule is hexagonal in shape and the outside has spaces containing vasculature and bile duct.
Describe the basic organization of a lubule
1. Hexagonal structre centered around a central vein which is responisible for draining the lobule.
2. Portal areas at the vertices contain branches of artery, vein, and duct.
3. Cords of hepatocytes radiate from central vein to form the internal structure of the lobule
4. Sinusoids are the spaces between the hepatocyte plates
5. Bile canaliculi and bile ducts transport bile and drain it.