The liver Flashcards
Where is the liver located?
Upper right quadrant, also . takes a little place in upper left quadrant
Sits into the diaphragm
Describe the gross anatomy of the liver
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
Describe the Coinaud classification
Liver can be split into 8 separate units, with each having its own hepatic (portal) vein.
Describe the blood supply of the liver
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*
What are the two methods of looking at a liver and what changes?
Morphological
- Lobules - has a portal containing bile duct, (HA and HPV)-sinusoid
Functional
- Acinis
- Blood and bile flow
What are the different cell types in the liver? What are their functions?
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
Where are these various cells located?
Sinusoid
- Kupffer
- Endothelial
Space of disse (endothelial and hepatocyte space)
- Stellate cell
Hepatocyte
What is an acinus?
A functional unit that refers to a cluster of cells Has 3 zones - Periportal - Transition - Pericentral
Which zones are susceptible to ischaemia and viral hepatitis?
Zone 3 and 1 respectively due to the distance to artery
What is bile?
Breakdown products containing broken-down red cells, cholesterol excretory products
Made by hepatocytes
Flows along canaliculi, opp to blood
What are the major metabolic roles of the liver?
Metabolism of glucose, protein and fat
How is glucose metabolised?
End result - stored as glycogen, which can be broken down to form glucose. If run out, then have to make it some other way
What happens when there is a lack of oxygen for muscles?
CORI CYCLE
Pyruvate is fermented, forming lactate
This is then converted to pyruvate in the liver.
Gluconeogenesis occurs, forming glucose
How are proteins metabolised?
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
Fat metabolism
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
Lipoprotein synthesis
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
Other hepatocyte function
Vitamin storage
- ADEK
- iron as ferritin
DETOXIFICATION
- P450 enzymes for Stage 1
- water added for Stage 2
