The liver

Question 1

Where is the liver located?

Answer 1

Upper right quadrant, also . takes a little place in upper left quadrant
Sits into the diaphragm

Question 2

Describe the gross anatomy of the liver

Answer 2

Four lobes, caudate, quadrate, left and right separated by falciform ligament, with gall bladder pointing out from under the right lobe

Collection of blood vessels above quadrate lobe, under . caudate

Question 3

Describe the Coinaud classification

Answer 3

Liver can be split into 8 separate units, with each having its own hepatic (portal) vein.

Question 4

Describe the blood supply of the liver

Answer 4

25% of cardiac output goes to liver

Dual blood supply

• both arteries and veins supply blood
• 20% arterial - oxygen
• 80% venous - HPV - to be cleaned*

Question 5

What are the two methods of looking at a liver and what changes?

Answer 5

Morphological
- Lobules - has a portal containing bile duct, (HA and HPV)-sinusoid

Functional

• Acinis
• Blood and bile flow

Question 6

What are the different cell types in the liver? What are their functions?

Answer 6

Hepatocytes
- 80pc

Endothelial cells
- lining and very leaky for movement of items

Cholangiocytes
- biliary lining

Kupffer cells
- fixed phagocytes and cytokine secretion

Hepatic stellate cells

• vit A storage cells and can be activated produce ECM - lay down excess and fibrosis
• important in cirrhosis - loss of healthy tissue

Question 7

Where are these various cells located?

Answer 7

Sinusoid

• Kupffer
• Endothelial

Space of disse (endothelial and hepatocyte space)
- Stellate cell

Hepatocyte

Question 8

What is an acinus?

Answer 8

A functional unit that refers to a cluster of cells
Has 3 zones
- Periportal
- Transition
- Pericentral

Question 9

Which zones are susceptible to ischaemia and viral hepatitis?

Answer 9

Zone 3 and 1 respectively due to the distance to artery

Question 10

What is bile?

Answer 10

Breakdown products containing broken-down red cells, cholesterol excretory products

Made by hepatocytes

Flows along canaliculi, opp to blood

Question 11

What are the major metabolic roles of the liver?

Answer 11

Metabolism of glucose, protein and fat

Question 12

How is glucose metabolised?

Answer 12

End result - stored as glycogen, which can be broken down to form glucose. If run out, then have to make it some other way

Question 13

What happens when there is a lack of oxygen for muscles?

Answer 13

CORI CYCLE
Pyruvate is fermented, forming lactate

This is then converted to pyruvate in the liver.

Gluconeogenesis occurs, forming glucose

Question 14

How are proteins metabolised?

Answer 14

Amino acids enter liver from diet or muscle cells, and forms secreted proteins such as plasma proteins, slotting factors and Lipoproteins

TRANSAMINATION
- move amino group to form non-essential amino acid

e.g.
Alanine + alpha-ketoglutarate
-> pyruvate + glutamate

DEAMINATION
- for usage of amino acid to 
  produce glucose
   - conversion of pyruvate to 
     glucose uses energy, as 
     does removal of nitrogen

e.g. Alanine is transaminated
The glutamate formed is deaminated, forming urea
Pyruvate from transamination then forms glucose

Question 15

Fat metabolism

Answer 15

Glycogen is preferred energy store, but fat is main store.

Fat is stored at TG in adipose, which is released as fatty acids.

Fatty acids undergo B oxidation and form Acetyl-coA for usage in TCA.

Or, liver can form ketones
- acetoacetate then moves to tissue as an energy source

Question 16

Lipoprotein synthesis

Answer 16

GLucose is converted to pyruvate and glycerol

Pyruvate then goes to AcetylcoA

AcetylcoA can generate FA or cholesterol

Glycerol and FA combine to form TAGs

Addition of apoprotein and cholesterol forms LIPOPROTEIN
- VLDL - FA to tissue
- LDL - cholesterol to tissue
- HDL - picks up excess  
             cholesterol

Question 17

Other hepatocyte function

Answer 17

Vitamin storage

• ADEK
• iron as ferritin

DETOXIFICATION

• P450 enzymes for Stage 1
• water added for Stage 2