Liver Function

Question 1

Why is the liver resilient?

Answer 1

It can regenerate cells destroyed by short time injury or disease

Question 2

Name the two types of liver cells

Answer 2

Hepatocytes and Kuppfer cells

Question 3

What is the bile canaliculi?

Answer 3

The small spaces between hepatocytes that form intrahepatic ducts where excretory products of the cells can drain

Question 4

What are the role of Kuppfer cells?

Answer 4

Macrophage cells that line sinusoids - act as phagocytes to engulf bacteria, debris and toxins

Question 5

List the 5 major functions of the liver

Answer 5

1. Metabolic
2. Synthetic
3. Storage
4. Detoxification
5. Excretory/digestive

Question 6

Give examples of metabolic functions of the liver

Answer 6

Carbohydrate metabolism - releases glucose by breaking down glycogen, stores glycogen

Protein metabolism - plasma proteins

Lipid metabolism and cholesterol

Question 7

Give an example of the synthesis function of the liver

Answer 7

Synthesises plasma proteins (albumin, clotting factors, c-reactive proteins)

Question 8

Give examples of the storage function of the liver (what does it store)

Answer 8

Iron, amino acids, glycogen, some vitamins (A, D, B12) and temporary lipid storage

Question 9

Give examples of the detoxification function of the liver

Answer 9

Detoxifies GIT metabolites, drugs, alcohol and paracetemol

Question 10

Give an example of the excretory/digestive function of the liver

Answer 10

Degrades bilirubin and removes excess cholesterol through bile

Question 11

What is bilirubin?

Answer 11

A bile pigment derived from the breakdown of red blood cells

Question 12

How is bilirubin transported to the liver?

Answer 12

By attaching to albumin in plasma (blood)

Question 13

Define total bilirubin.

Answer 13

The sum of conjugated + unconjugated bilirubin

Question 14

Define jaundice and what symptoms occur

Answer 14

A condition of increased serum bilirubin levels and it’s deposition in the skin, mucous membranes and sclera (White of the eye) - characterised by yellow colouring (icterus)

Question 15

What are the 3 types of jaundice

Answer 15

1. Pre hepatic jaundice - problem occurs before the liver
2. Hepatic jaundice - problem occurs in liver
3. Post hepatic jaundice - problem occurs after liver

Question 16

What is prehepatic jaundice and what is it caused by

Answer 16

Occurs prior to liver metabolism - caused by malaria, sickle cell disease or haemolytic disease of the newborn

Question 17

What is intrahepatic jaundice and what are the 3 types

Answer 17

Problem resides in the liver due to 1) hepatocelluar damage, 2) inherited hyperbilirubinemia, or 3) Neonatal physiological jaundice in newborn

Question 18

Define neonatal physiological jaundice

Answer 18

Transient (short term) immaturity of the liver = delay in being able to produce the UDPG transferase enzyme for conjugation of bilirubin

Question 19

Prehepatic jaundice will lead to what pathophysiological states?

Answer 19

Increased plasma bilirubin
Increased unconjugated bilirubin
Increased urine urobilinogen

Question 20

Posthepatic jaundice will lead to what pathophysiological states?

Answer 20

Increased conjugated bilirubin
Increase plasma bilirubin
Increased plasma GGT and ALP
Decreased urine urobilinogen
Positive urine bilirubin

Question 21

Define posthepatic jaundice

Answer 21

Partial or complete obstruction of the biliary tree preventing flow of conjugated bilirubin into bile canaliculi therefore unable to reach the gut (stools are clay coloured due to bilirubin not reaching gut)

Question 22

What are the 3 types of liver function tests?

Answer 22

1. Function - albumin, clotting, bilirubin
2. Damage - enzyme assays
3. Cholestasis - enzyme assays

Question 23

What are the different tests to measure liver function?

Answer 23

• tests that measure hepatic cellular ability
• tests that measure nitrogen metabolism
• tests that measure bilirubin metabolism

Question 24

What molecules are tested for in hepatic cellular ability tests

Answer 24

albumin - decreased in chronic liver disease (not useful for acute due to its long half life)
prothrombonin time - increased in liver disease due to inadequate production of clotting factors or inadequate absorption of vitamin K from intestine due to disruption of bile flow
lipids - hepatic disorders often disrupt lipoprotein metabolism (not liver specific)

Question 25

Describe nitrogen metabolism tests and what you would see

Answer 25

Ammonia is toxic and usually converted to urea in liver, increased plasma ammonia levels indicate liver failure which can be due to newborn liver immaturity or urea cycle enzyme deficiencies

Question 26

What enzyme is more liver specific - ALT or ASP

Answer 26

ALT (alanine aminotransferase) as it is produced primarily by hepatocytes, ASP is produced by hepatocytes but also many other tissues

Question 27

Define cholestasis

Answer 27

Blockage of bile duct so no bile can flow from liver to intestine

Question 28

What are the 2 types of cholestasis

Answer 28

Intrahepatic cholestasis - occurs before the liver (from cancer or biliary cirrhosis)
Extrahepatic cholestasis - occurs after the liver (from gallstone or tumor blocking)

Question 29

What enzymes are used to measure cholestasis?

Answer 29

GGT and ALP

Question 30

Is GGT or ALP more specific in liver?

Answer 30

GGT as ALP is also produced in the bone, intestine and placenta

Question 31

What are the 2 limitations of using liver enzymes to detect liver disease

Answer 31

Acute disease - dont correlate with disease severity or prognosis
Chronic - can only tell us something is wrong with liver, not the severity or progression of disease