liver histology

Question 1

1. Describe the basic pattern of blood flow through the liver, including flow from the hepatic portal vein and separately from the hepatic artery.

Answer 1

• 70-75% of blood supply from hepatic portal vein.
• 25-30% from hepatic artery which branches from the celiac trunk.
• Blood is drained via hepatic veins which empty into the inferior vena cava.
• First structure receiving blood from digestive system. Microstructural arrangement of hepatocytes maximizes area of contact with the blood.
• Why is this good to have? To filter toxins. Nutrition and storage of glucose.
• (Biliary secretion is sealed off from blood supply via tight junctions.)

Question 2

1. Be able to describe the three lobular descriptions of the basic microstructural organization of the liver.

Answer 2

Classical
- Hexagonal arrangement of hepatocyte arranged radially around central vein.
- At each of the six vertices, there is a portal triad (interlobular vessels from hepatic portal vein and hepatic artery, portal vein, bile duct).
Portal
- Similar to above, but shape is triangular between three ventral veins, so organized around a portal triad.
- Bile secretory functional unit.
Acinar
- Another structural definition in terms of blood delivery.
- Short axis lies between two portal triads and the long axis between two central veins.

Question 3

2. Be able to describe the flow of bile within the liver.

Answer 3

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Question 4

4. Describe the functions of the hepatocyte.

Answer 4

• Take up glucose after a meal and store it as glycogen preventing large oscillations in blood glucose levels. Glycogen is converted to glucose during fasting periods.
• Produce major blood proteins, including albumin, clotting factors like fibrinogen and prothrombin.
• Produce the lipoproteins.
• Take up various lipid-soluble toxins and bilirubin, and can detoxify these substance biochemically.
• Eliminated excess cholesterol in the form of bile.

Question 5

3. Describe the relationship of the hepatocyte to the blood and bile from a structural viewpoint.

Answer 5

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Question 6

4. Be able to define the arrangement of the liver sinusoidal endothelial cells and Kupffer cells within the liver.

Answer 6

• Outside the microvillar surface of hepatocytes is a perisinusoidal space occupied by a fine meshwork of reticular fibers separating the hepocytes from a fenestrated endothelial layer.
• Kupffer cells (liver macrophages) make up part of this endothelial layer. They are derived from the monocyte lineage. These cells are distinguishable by large nuclei and rapid phagocytosis of particulate materials. Play a role in defense.

Question 7

5. Describe the walls of the bile canaliculi, canals of Hering and interlobular bile ducts.

Answer 7

• Bile canaliculi result from apposed grooves of adjacent hepatocytes.
• These lead to small bile ductules called canals of Hering.
• From there, ductules lead to the interlobular bile ducts of the portal triad.
• Then lobar ducts connect to form the common hepatic duct.

Question 8

8. Be able to describe the mucosa of the gall bladder and explain what it does and what is unique about its structure as compared to other digestive mucosae.

Answer 8

• The gall bladder is a distensible pouch connected to the common hepatic duct via the cystic duct.
• The gall bladder stores and concentrated bile.