Liver

Question 1

Flow of fluids into and out of the liver lobule

Answer 1

• On the periphery of the liver lobule there is a hepatic artery and portal vein which both enter the lobule
• their blood mixes together in a sinusoid
• Flows down the central vein where it extis the lobule through hepatic vein
• Flowing in the opposite direction (out to periphery)
• -Bile fluid in bile ducts
• -Some lymphatic vessels also flowing out of the lobule

Question 2

Portal Triad

Answer 2

• Hepatic Arteriole
• Portal Venule
• Bile Ductule- Hering’s Canal
• Lymphatic vessel

Question 3

Hepatic Sinusoids

Answer 3

• Both arterial and portal blood mix in the sinusoids as they flow towards the central vein
• holes in the endothelial lining of the sinusoid

Question 4

Hepatocytes

Answer 4

• main cell type of the liver
• Sinusoidal face contains an abundance of microvilli
• -increases surface area
• -help absorb the components of blood into the liver
• two adjacent hepatocytes from the bile canaliculus through tight junctions

Roles

• Synthesis of plasma proteins (albumin, fibrinogen)
• Storage of glucose as glycogen
• convert amino acids into glucose
• detoxification and conjugation of ingested toxins

Question 5

Space of Disse

Answer 5

• Immediately adjacent to hepatocytes

- between hepatocytes and fenestrated epithelium

Question 6

Kupffer Cells

Answer 6

• derived from monocytes
• phagocytic - phagocytize foreign materials and aged red blood cells in sinusoids of the liver
• mainly in sinusoids

Question 7

Ito Cells

Answer 7

• Fat storing cells
• play a role in fat storage
• play a role in disease (cirrhosis of the liver)
• -secrete a lot of type I collagen under disease
• -leads to cirrhosis of thel iver
• -cirrhotic liver = too much connective tissue
• tend to be in the space of disse
• also called lipocytes
• also called hepatic stellate cells

Question 8

Somatomedins

Answer 8

• IGF’s
• Make their way to cartilage
• stimulates proliferation of chondrocytes and chondroblasts

Question 9

Extra Medullary Hematopoiesis in the liver

Answer 9

• If you have damage to bone marrow
• Secondary hematopoiesis in the liver
• related to fetal function of the liver (hepato/spleno/thymic phase)

Question 10

Formation of Bilirubin

Answer 10

1. Kupffer cells - taking up aged red blood cells
2. Hemoglobin is stripped of heme molecule by the macrophages
   - globin is broken down into amino acids and is recycled
   - heme is stripped of iron which is recycled
3. Heme is converted to biliverdin
   - via heme oxygenase
4. Biliverdin is further catabolized to bilirubin
5. Bilirubin is released by macrophage and taken up by liver
   - bound to albumin and taken up by the liver
6. In the liver
   - Bilirubin is made into bilirubin glucuronide via glucuronyltransferase
   - more water soluble
   - What is excreted into bile canaliculus and makes its way into the gall bladder and large intestine

Question 11

Bile Canaliculus

Answer 11

• made via tight junctions of adjacent hepatocytes
• bile is running through this to the periphery of the liver (opposite direction as blood)
• bile acids such as cholic acid are synthesized in hepatocytes and secreted into the bile canaliculus

Question 12

Classic Lobule

Answer 12

• portal triad
• arteriole and venous blood flowing to central artery
• the bile canaliculus and lymphatics flowing back out

Question 13

Portal Lobule

Answer 13

• Bile flowing from center to portal triad

Question 14

Portal Acinus

Answer 14

• Most oxygenated zone (zone I) is where the portal triads are due to the blood vessels
• As you flow from triad to central vein there is a reduction of oxygen concentration
• Central vein will have the least amount of oxygen
• Zone I is most oxygenated
• Zone II is least oxygenated

Question 15

Pit cells

Answer 15

• NK cells

- in the sinusoids

Question 16

Change in metabolic functions of Hepatocytes as you move from portal triad to central vein

Answer 16

• reduction in oxygen
• reduction in hormones
• increase in glycolysis enzymes
• reduction in glucose liberating enzymes
• reduction in fatty acid oxidation enzymes
• increase in fatty acid synthesizing enzymes