Function of the Liver and Hepatobiliary System

Question 1

What organs is the liver associated with?

Answer 1

Associated with the other abdominal organs and organs of the digestive system.

Question 2

What is the liver?

Answer 2

Largest solid organ in the upper right quadrant and is composed of 2 lobes.

Question 3

Where is the liver located?

Answer 3

In the upper right quadrant

Question 4

What are some genetic variations of the livers anatomy?

Answer 4

Hereditary anatomical displacement,

accessory lobes

Question 5

What internal factors are associated with gross liver anatomy?

Answer 5

Portal thrombosis, cardiac cirrhosis, fibrosis and atrophy

Question 6

What external factors are associated with gross liver anatomy?

Answer 6

Impression effects

Question 7

What suggests that a patient may have liver disease when presented with fatigue and weight loss?

Answer 7

Raised liver enzymes
Increased prothrombin time
reduced serum albumin

Question 8

Where does bile drain into?

Answer 8

Hepatic bile drains directly into the duodenum to enable the digestion of fats.

Question 9

How can the liver be functionally divided up?

Answer 9

Liver can be divided up into segments based upon the blood supply and bile drainage.

Question 10

What is the lobule/acinus?

Answer 10

The functional units of the liver

Question 11

What are the lobule/acinus composed of?

Answer 11

Plates of hepatocytes, sinusoidal channels, inlet and exit blood vessels and bile canaliculi.

Question 12

Where does blood come from to the liver?

Answer 12

Portal vein - venous blood from the gut (75%)

Hepatic artery - arterial blood (25%)

Question 13

What is the blood content of the liver and what is its passage through the liver?

Answer 13

Blood content makes up about 30% of the liver and up to 15% of total blood content.

Enters the liver
Mixes in the sinusoids
drains via hepatic veins into the IVC

Question 14

How much blood enters the liver per min?

Answer 14

roughly 1.3L/min around 25% of cardiac output

Question 15

What is the function of the connective tissue in the liver (liver stroma)?

Answer 15

For metabolic support and scaffolding.

Acts as a capsule to protect the liver and the biliary tree.

Question 16

What is the connective tissue of the liver composed of?

Answer 16

ECM materials such as collagen etc.

Also made up of stellate cells, glycoproteins, integrins.

Question 17

What happens to the structure of the lobule in a fibrotic liver?

Answer 17

The hexagonal architecture becomes disrupted and the patient will lose hepatocytes and have an increased build up of connective tissue.

Question 18

What are hepatocytes?

Answer 18

60-65% of liver tissue
100 billion cells
Large cells (due to their range of functions)
polarised polyhedral epithelial cells (meaning they have different functions across the plains of the cell)
low mitotic index
Secretions are located close to the sinusoids for early drainage.

Question 19

What are the functions of the hepatocytes?

Answer 19

Protein secretion
Bile secretion
Storage
Metabolism
Detoxification and inactivation (drugs, alcohol)

Question 20

What is the biliary Epithelium?

Answer 20

Form collecting vessels of increasing size with the aim to seal in all the bile to prevent it leaking.
Also used in secretion of bile.

Question 21

What do the endothelial cells of the liver do?

Answer 21

Form a barrier tissue which acts as a filter lining the hepatic vasculature.
They protect the parenchyma from blood cells, bacteria and viruses.
Functions:
- Anti thrombogenic surface
- regulation of coagulation
- regulation of leukocyte traffic.

Question 22

What are Kupffer cells?

Answer 22

Hepatic macrophages located within the sinusoids
80% of all macrophages in the body
Involved in phagocytosis, regulation of the microcirculation, removal of endotoxin
Very active cells
Can produce cytokines, present antigens and stimulate immune responses

Question 23

What are stellate cells of the liver?

Answer 23

Star shaped cells with multiple membrane processes and branching structure.
Sit in the sinusoids
Store vitamins

Question 24

What are the digestive functions of the liver?

Answer 24

Carbohydrate and fat metabolism (can also be used to produce glycose)
Storage of vitamins and minerals

Question 25

What is the function of the liver for cholesterol synthesis?

Answer 25

Liver can synthesise cholesterol which is an essential component for cell membranes. Also an important component of bile acids, steroids, hormones.

Question 26

What is the function of the liver in bile production?

Answer 26

About 0.5L if bile is produced a day by hepatocytes which isn't enough so some of it is recycled to be reused when needed. Bile is key for emulsification of fats. Also for excretion of some substances which can't be cleared by the kidney.

Question 27

What is the immune function of the liver?

Answer 27

Protection against pathogen arriving in blood. Phagocytosis of old or dying cells innate immune functions induction of tolerance so the body ignores proteins that will not cause damage.

Question 28

How is Bilirubin produced?

Answer 28

Haem --(oxidised) --> to green Biliverdin --(biliverdin reductase)--> to bilirubin

Question 29

What is are the proportions of immune cells in the liver?

Answer 29

The liver selects the important immune cells to sit in zone 1 to prevent infection be pathogens.

Question 30

What are the detoxification and elimination functions of the liver?

Answer 30

``` Urinary excretion (solubilisation of compounds) Biliary excretion (lipophilic compounds) ``` Biotransformation of Drugs: Phase 1 - Oxidation or reduction to make soluble (P450) Phase 2 - Conjugation to make water soluble Elimination of ammonia by-product of protein metabolism.

Question 31

What are the P450 enzymes?

Answer 31

enzymes used to metabolise potentially toxic compounds such as drugs and bilirubin.

Question 32

What are the useful proteins produced by the liver?

Answer 32

``` Albumin (50%) of all plasma proteins Fibronectin and components of the coagulation cascade Plasminogen Alpha -1 antitrypsin Transferrin Hepcidin ```

Question 33

What are the stages of liver damage?

Answer 33

Healthy liver Fatty liver - deposits of fat lead to liver enlargement Liver fibrosis - scar tissue forms Liver Cirrhosis - Growth of connective tissue destroys liver cells

Question 34

What are the main causes of liver disease?

Answer 34

Alcohol abuse Obesity - metabolic liver disease Viral infection - Hepatitis C Virus (HCV)

Question 35

What is Hepatitis?

Answer 35

Liver inflammation (non-viral) caused by liver disease either acute or chronic.

Question 36

What can liver cirrhosis cause?

Answer 36

Leads to life threatening complications causing renal failure, varices in the oesophagus, ascites and spleen problems.

Question 37

What kind of liver tests can be done for diagnosis?

Answer 37

Bilirubin concentration Blood tests Liver enzyme concentrations Biopsy

Question 38

What are the pathways that drive the development of fibrosis of the liver?

Answer 38

Damage - Virus/toxin/autoimmunity Acute hepatitis Chronic hepatitis Liver Fibrosis

Question 39

What is liver cirrhosis?

Answer 39

Where the liver does not function properly due to long term damage caused by the main causes.

Question 40

What is liver fibrosis?

Answer 40

Formation of abnormally large scar tissue in the liver.