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Dentistry Biological Science > Liver & Pancreas > Flashcards

Flashcards in Liver & Pancreas Deck (31)
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1
Q

What are the two ducts in the pancreas?

A
  • main pancreatic duct

- common bile duct

2
Q

What enzymes are made in the pancreas?

A

Majority used in duodenum.

3
Q

What important substance does the pancreas make?

A

Bile

4
Q

What are the two types of cells in the pancreas?

A
  • Exocrine (salivary glands)

- Endocrine (islets of Langerhans)

5
Q
Pancreas:
What does the exocrine part look like?
What is the structure?
How does it secrete?
Are there any mucus producing cells?
What cell is most abundant here?
A
  • parotid gland
  • typical branched acinar structure
  • merocrine secretion
  • no mucus producing cells here
  • enzyme producing cells are more abundant cell here
6
Q

What cells line the lumen of the pancreas?

Explain where the nucleus is

A

Centroacinar cell

All enzyme producing cells have the nucleus at the bottom of the cell to move the nucleus so efficient secretion can occur. Occasionally you have a nucleus in the middle of the cell which are the centroacinar cells.

7
Q

What is the function of the centroacinar cell?

A

To produce bicarbonate ions. The secretions pass into the intercalated duct and then into the excretory duct.

8
Q

Explain the two differences between the pancreas and the salivary glands down the microscope

A

Pancreas:

  • No striated ducts
  • Centroacinar cells

Salivary Gland:

  • Striated ducts abundant
  • No centroacinar cells
9
Q

Why do the islets of langerhans have a high blood supply?

A

These cells trap around the capillary so can efficiently deposit their hormone secretion into the bloody supply.

Balls of cells producing insulin, glucagon, somatostatin, pancreatic polypeptide and vasoactive intestinal peptide.

10
Q

What happens with a pancreatic tumer?

A

Causes enzymes to enter the body cavity which causes cells to digest the body.
Makes pancreatic surgery hard.

11
Q

Give the 8 functions of the liver:

A

1) Exocrine = production of bile
2) Processes absorbed nutrients
3) Carbohydrate, fat and protein metabolism
4) Stores - carbohydrates, lipids, vitamins
5) Synthesises - plasma proteins (involved in transport), lipoproteins
6) Detoxification of ingested toxins, drugs
7) Destroys red blood cells and reclaims iron
8) Site of haematopoiesis in embryo

12
Q

Explain the structure and organisation of the liver

A

Roughly hexagonal but less distinct due to there being less connective tissue between lobules.

Has a central vein in the middle - where the processed blood exits the liver lobule.

Triads - where the blood enters the liver.

13
Q

What are the two sources entering the lobule?

What exits the lobule?

A

1) The portal vein (brings blood from the small intestine containing the absorbed nutrients)
2) Hepatic artery (brings oxygenated blood)

Bile moving out to the bile duct.

14
Q

How are hepatocytes arranged?

A

Arranged in rows
- blood flows in-between

Major cell type is in hepatocyte. They sit aside sinusoids. They are cuboidal either occurring in one or two layers.

15
Q

What two cells line the sinusoids?

A
  • Endothelial cells

- Kupffer cells (phagocytic cells)

16
Q

What do hepatocytes have which then extend?

A

Microvilli which extend into space of Disse.

17
Q

What are the cells called with are formed in the space of Disse?

What can these cells transform into and why?

A

Stellate cells (has lipid droplets in them which store vitamin A).

Into myofibroblasts in response to inflammatory stimuli. They begin to lead down collagen which can leads to cirrhosis.

18
Q

When can the liver not regenerate?

A

If cirrhosis has occurred.

19
Q

Why are there gaps in the endothelial cells?

A

Where the microvilli project to allow the lipid part of the blood to come in direct contact with the hepatocyte to increase efficiency of uptake and to cause proteins from the hepatocyte to enter the blood.

20
Q

What makes hepatocytes specialised?

A
  • highly compact
  • surfaces are specialised in different ways
  • polarised (has a direction) along all axis
21
Q

What are the things which you can secrete and absorb?

A

Secretion: albumin, fibrinogen (plasma proteins), clotting factors

Absorption: blood-borne substances (food, drugs)

22
Q

Explain the hepatocyte metabolic activity

A

Crowded with organelles, reflecting the high biosynthetic and degradative activity.
Lots of smooth endoplasmic reticulum to produce vesicles for secretion.

23
Q

How does bile leave the liver? Explain this

How do we prevent bile from getting between the cells?

A

Bile canaliculi keeps blood and bile separate. They have microvilli in them.

Tight junctions between cells.

24
Q

What are the two things bile contains?

A
  • bile salts (sodium glycocholate, deoxycholate, taurocholate) synthesised from cholesterol, acts as detergent to emulsify fats in the duodenum
  • bile pigments (bilirubin and biliverdin) breakdown products of haemoglobin, lysosomes fuse with them and then broken down, products of Hb breakdown goes into the bile
25
Q

What is an acinus formed from?

A

Two adjacent triads

26
Q

What are the 3 zones in hepatocytes?

What is metabolised in region 1 and 3?

A

1: blood most oxygenated, nutrient-rich
2: intermediate
3: blood depleted of oxygen and nutrients

Region 1 metabolises glucose. Region 3 metabolises glycogen.

27
Q

What is toxic to region 1 and region 3?

A

Region 1 - the toxin

Region 3 - byproducts of the toxin

28
Q

Explain the breakdown of paracetamol?

A

Paracetamol is metabolised by P450s producing a derivative. Byproduct of metabolism called quinone is what is toxic to the body. This is going to kill region 1 cells (closest to central vein).
The affect of this on region 1 is irreversible.

29
Q

What does cirrhosis do to the lobule body?

A

Cirrhosis has deposition of extra cellular matrix within lobule body which prevents diffusion of blood from the triad across the lobules.

30
Q

Give as many details on the gall bladder as possible

A
  • Stores and concentrates bile (about 50ml)
    Na+ - K+ ATPase pumps in basal and lateral membranes of epithelium

Walls of the gall bladders in fold.
One cell type present.
Brush border to increase efficiency of pumping ions across it.
Thin layer of smooth muscle around this.
Tall, simple columnar epithelium with an irregular brush border.
Cholcystokinin causes bile to be released by causing the smooth muscle to contact when food arrives.

31
Q

Why is there gaps between the basal surfaces of adjacent cells in the gall bladder?

A

Due to the influx of water following the pumping out of NaCl into the interstitial space.

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