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Flashcards in Liver Deck (16):
1

Flow of fluids into and out of the liver lobule

- 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

2

Portal Triad

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

3

Hepatic Sinusoids

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

4

Hepatocytes

- 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

5

Space of Disse

- Immediately adjacent to hepatocytes
- between hepatocytes and fenestrated epithelium

6

Kupffer Cells

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

- mainly in sinusoids

7

Ito Cells

- 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

8

Somatomedins

- IGF's
- Make their way to cartilage
- stimulates proliferation of chondrocytes and chondroblasts

9

Extra Medullary Hematopoiesis in the liver

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

10

Formation of Bilirubin

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

11

Bile Canaliculus

- 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

12

Classic Lobule

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

13

Portal Lobule

- Bile flowing from center to portal triad

14

Portal Acinus

- 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

15

Pit cells

- NK cells
- in the sinusoids

16

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

- 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