13.12 Histology: Liver and Pancreas Flashcards Preview

Week 13- Gastrointestinal > 13.12 Histology: Liver and Pancreas > Flashcards

Flashcards in 13.12 Histology: Liver and Pancreas Deck (24)
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1
Q

What is the liver derived from?

A

Endoderm

2
Q

How many surfaces does a hepatocyte have and how wide is it across?

A

Polyhedral, 25um across

3
Q

How many nuclei and how many copies of DNA do hepatocytes have?

A

1-2 nuclei

tetraploid or polyploid

4
Q

What structures do hepatocytes contain (and how do these reflect their purpose)?

A

Rough ER, golgi, secretory vesicles (PRO synthesis)

Prominent smooth ER (FAT metabolism)

Many mitochondria

5
Q

What type of cells are hepatocytes?

A

Epithelial cells (replaced regularly by division of existing hepatocytes)

6
Q

Hepatocytes comprise ___% of liver weight

A

75%

7
Q

What are the blood supplies for the liver?

A

Majority, venous blood from gut (hepatic portal system)

Also arterial supply

8
Q

What surrounds the liver?

A

A thin capsule (Glisson’s capsule)

9
Q

What fibres are the hepatocytes supported by?

A

Reticular fibres (collagen type III)

10
Q

How are hepatocytes organised?

A

Into lobules (stacks of hepatocytes in plates)

11
Q

How does blood flow into the liver?

A

Into lobule, then across to central vein (outside in)

12
Q

What is the portal triad comprised of?

A

Hepatic portal vein (deoxygenated blood from gut), hepatic artery and bile duct

13
Q

Where do sinusoids converge?

A

On the central vein (carrying blood to hepatic vein and out of liver)

14
Q

What is a sinusoid?

A

A network that veins and arteries give rise to that carry blood to plates of hepatocytes

15
Q

What is the Space of Disse?

A

A place where the hepatocytes are directly bathed by plasma (too small for cells)

16
Q

How is a hepatic acinus organised?

A

Zone 1: best O2 supply

Zone 2

Zone 3: worst O2 supply (closest to central vein)

17
Q

Which zone’s hepatocytes are the first to die if there are toxins or metabolites?

A

Toxin: Zone 1 dies

Metabolites: Zone 3 dies (low concentration of nutrients)

18
Q

What are the differences in the three zones in hepatic acini?

A

Zone 1: high in O2, toxins, nutrients

Zone 3: low in O2, toxins, nutrients

19
Q

How is bile produced?

A

Hepatocytes (bile salts from cholesterol)

20
Q

Which direction does bile flow in the liver?

A

Outwards (collected into ducts)-opposite direction to blood

21
Q

How is bile reabsorbed?

A

In the small intestine (concentrates bile salts and pigments), approx 90%

22
Q

How does the gall bladder know when to contract to secrete bile?

A

Fat–>CCK into blood–>gall bladder contracts–>relaxation of sphincter of Oddi–>squirt of bile into duodenum

23
Q

Where do the ducts draining the pancreas join the common bile duct?

A

At the sphincter of Oddi

24
Q

Why doesn’t the pancreas digest itself?

A

Zymogen enzymes are secreted in an inactive form and activate upon hitting bile/other enzymes