Liver

Question 1

What are the major functions of the liver?

Answer 1

Digestive:
1. Bile salt production

Non-Digestive:
2. Metabolic processing of absorbed nutrients.
3. Degrading body wastes, drugs, hormones, and FB.
4. Synthesising plasma proteins (e.g., angiotensinogen).
5. Storing glycogen, fats, iron, copper, and many vitamins
6. Excreting cholesterol and bilirubin
7. Activating Vitamin D
8. Secreting hormones (e.g., hepcidin, thrombopoietin, IGF-1)
9. Producing acute phase inflammatory proteins
10. Removing bacteria and expired red blood cells (Kupffer cells)

Question 2

Describe the route of liver blood flow.

Answer 2

Oxygenated blood flow from hepatic artery + deoxygenated, but nutrient-rich blood from hepatic portal vein -> liver sinusoids -> central vein -> hepatic vein -> inferior vena cava -> right atrium of heart.

Question 3

Describe the rout of liver bile flow.

Answer 3

right hepatic duct + left hepatic duct -> common hepatic duct + cystic duct -> common bile duct + pancreatic duct -> duodenum.

Question 4

The liver can be organised into three units depending on ____ and ____. What are they?

Answer 4

Structure and Function

Classic lobule
Portal lobule
Classic acinar

Question 5

What are the properties of classic lobule?

Answer 5

Hexagon-shaped plates
Central vein with radiating strands of hepatocytes
Portal triads in corners of hexagon
Blood flows from periphery to centre

Question 6

What are the properties of portal lobule?

Answer 6

Based on exocrine / secretory function of liver
Bile duct in centre
Central vein in each corner of triangle

Question 7

What are the properties of liver acinus?

Answer 7

Based on blood supply within liver
Oval-shaped arrangement
Short axis defined by two portal triads
Long axis defined by two central veins

Question 8

What are the 3 zones of liver acinus?

Answer 8

Zone 1 - perilobular
First to show effects of bile obstruction; last to die if circulation impaired.

Zone 2 - mid zone

Zone 3 - centrolobular
Last to show effect of bile obstruction; first to die if circulation impaired.

Question 9

What are the 4 cell types in liver?

Answer 9

1. Kupffer cells
2. Ito cells
3. Endothelial cells
4. Hepatocytes

Question 10

What are the properties of hepatocytes?

Answer 10

1. polyhedral cells that make up ~80 % of the liver.
2. Arranged in plates one-cell thick, bordered by sinusoids and canaculi.
3. Metabolically active cells - many organelles and enzymes, high energy requirements.
4. stores glycogen.

Question 11

What are the properties of endothelial cells?

Answer 11

1. line the sinusoids.
2. Discontinuous arrangement (fenestrations).
3. Permits exchange of molecules.

Question 12

What are the properties of Kupffer cells?

Answer 12

1. Phagocytic cells (macrophages).
2. AKA reticuloendothelial cells.
3. Fixed within sinusoids.
4. Destroy expired blood cells, bacteria, and foreign matters in blood from GIT.

Question 13

What are the properties of Ito cells?

Answer 13

1. Store lipids and Vitamin A.
2. Produce reticular fibres and fibrous tissues.

Question 14

How is liver physiology relevant to dental science?

Answer 14

Liver pathology can manifest in the oral cavity.

Some examples:
1. viral hepatitis.
2. alcoholic liver disease
3. cirrhosis
e.g., jaundice (esp. oral mucosa), parotid enlargement, bleeding tendency (esp. gingiva), dry mouth etc.

And dental treatment may need to be modified in affected patients.

The liver is the main source of metabolism for many drugs:
1. local anaesthetics (e.g., lidocaine, bupivacaine).
2. Analgesics (e.g., aspirin, paracetamol).
3. Sedatives (e.g., diazepam, pentobarbital).
4. Antibiotics (e.g., erythromycin, tetracycline).