Unit 4 - The liver

Question 1

What is the largest internal organ of the body?

Answer 1

The liver

Question 2

What percentage of resting cardiac output is delivered to the liver?

Answer 2

30%

Question 3

What percentage of total blood volume is held in the liver?

Answer 3

13%

Question 4

What unique feature does the liver have?

Answer 4

Regenerative

- can regenerate to within 5 - 10% of its original size

Question 5

What is the functional unit of the liver?

Answer 5

Hepatocyte
the major parenchymal cells in the liver, play pivotal roles in metabolism, detoxification, and protein synthesis. Hepatocytes also activate innate immunity against invading microorganisms by secreting innate immunity proteins.

Question 6

How are hepatocytes arranged in the liver?

Answer 6

In lobules

Question 7

What percentage of the blood delivered to the liver is delivered via the hepatic portal vein?

Answer 7

70%

Question 8

What percentage of the blood delivered to the liver is delivered via the hepatic artery?

Answer 8

30%

Question 9

Which vessel takes blood away from the liver?

Answer 9

Hepatic vein

Question 10

What makes up the portal triad?

Answer 10

• hepatic artery
• hepatic portal vein
• bile duct

Question 11

What is a sinusoid?

Answer 11

Capillary space in the liver between hepatocytes

Question 12

What is the function of the sinusoid?

Answer 12

Blood delivered to the sinusoid is exposed to the hepatocytes

Question 13

What is the function of the liver?

Answer 13

• storage
• clearance
• filtration
• secretion
• excretion
• synthesis
• metabolism
• homeostasis

Question 14

How does the liver carry out detoxification?

Answer 14

Destroys endogenous and exogenous substances
- metabolism
Destroys cellular debris and invading bacteria
- phagocytosis
Deamination of amino acids
Removal of bilirubin
- build up would lead to jaundice
Hormone deactivation

Question 15

What are the two classifications of liver disease?

Answer 15

• acute

- chronic

Question 16

What are the characteristics of acute liver disease?

Answer 16

Less than 6 months duration
Often involves spontaneously
- self limiting
Rapid decline in liver function
May be asymptomatic
100% association with encephalopathy and coagulopathy
Can result in acute liver failure (ALF)

Question 17

What are the characteristics of chronic liver disease?

Answer 17

Over 6 months duration
Often symptomatic
Secondary to long-standing cell damage
Permanent structure change
Loss of normal liver architecture
Cirrhosis
- fibrous scars
- divides the liver in nodulesWhat

Question 18

What are the causes of liver disease?

Answer 18

• viral infection
• alcohol
• non-alcoholic fatty liver disease
• non-alcoholic steatohepatitis
• cholestasis
• intra-hepatic (in liver)
• extra-hepatic (related to pancreas)
• immune disorders
• vascular abnormalities
• metabolic disorders
• genetic disorders
• drugs

Question 19

What five viruses are responsible for liver disease?

Answer 19

Hep A - faecal contamination of food or drink

Hep B - blood/blood contamination

Hep C - blood/blood contamination

Hep D - have to have Hep B to get Hep D

Hep E - faecal contamination of food or drink

Question 20

What is the route of infection for hepatitis A and E?

Answer 20

Faecal contamination of food or drink

Question 21

What is the single most significant cause of liver disease in the Western world?

Answer 21

Alcohol consumption

Question 22

How does alcohol cause liver disease?

Answer 22

Fibrous tissue in liver increases resistance to blood flow from the portal system resulting in portal hypertension (PHT)
As liver cell death continues it leads to liver failure
Rate of progression (and regression) linked to further alcohol consumption
- eventually leads to cirrhosis (scar tissue)

Question 23

What is non-alcoholic fatty liver disease (NAFLD)?

Answer 23

Damage caused by fat in the diet

Question 24

What is non-alcoholic steatohepatitis (NASH)?

Answer 24

An advanced form of non-alcoholic fatty liver disease (NAFLD)

• NAFLD is caused by build up of fat in the liver
• when this build up causes inflammation and damage, it is known as NASH, which can lead to scarring of the liver

Question 25

What is cholestasis?

Answer 25

Blockage of bile release

Question 26

What are the two types of liver disease caused by drugs?

Answer 26

Type A | Type B

Question 27

What is Type A drug damage to the liver?

Answer 27

Dose related - withdrawal of precipitating drug results in reversal - paracetamol - tetracyclines - methotrexate

Question 28

What is Type B drug damage to the liver?

Answer 28

``` Idiosyncratic - bizarre! Hypersensitivity or metabolic - not related to dose - just exposed to drug ```

Question 29

How has liver mortality changed since 1970?

Answer 29

Increased by 500%

Question 30

How has alcohol-related hospital admissions (specifically liver admissions) changed between 2002 - 2012?

Answer 30

Doubled

Question 31

What are the symptoms of liver disease?

Answer 31

``` Non specific symptoms - weakness - fatigue - general malaise Poor nutrition status - chronic - weight loss - anorexia - advanced - loss of muscle bulk Abdominal discomfort/pain Tenderness over liver - upper right quadrant Jaundice - yellowing of skin and sclera ```

Question 32

What are the cutaneous signs of liver disease?

Answer 32

``` Hyperpigmentation - darker patches of skin Scratch marks - itchy Spider naevi - surface vessels Non specific - palmar erythema - red palms - Dupuytren's contracture - involuntary contracture of fingers to palms - nail changes - finger clubbing ```

Question 33

What are the abdominal signs of liver disease?

Answer 33

``` Distension Hepatomegaly - enlargement of liver Splenomegaly - enlargement of spleen Umbilical and paraumbilical veins - greeny/blue veins under surface of skin ```

Question 34

What are the symptoms of jaundice?

Answer 34

Yellowing of the skin and sclerae | - sudden onset in adults should be investigated urgently

Question 35

What are the causes of jaundice?

Answer 35

``` Hepatocellular - drugs - hepatitis - tumour Cholestatic - obstruction of bile flow - tumour Prehepatic - increased blood breakdown ```

Question 36

What causes pruritis (itching of the skin) associated with liver disease?

Answer 36

Deposition of bile salts in the skin Concentration does not correlate with severity - low concentrations can be very itchy! Most debilitating in cholestatic conditions - obstruction relieved by endoscopy, radiology, surgery Pharmacological treatment favoured for other causes

Question 37

What are the signs of portal hypertension in liver disease?

Answer 37

``` Increased pressure in portal venous system leads to - collateral vein formation - leaky - risk of internal bleeding - shunting of blood to systemic circulation Contributes to - formation of ascites - development of encephalopathy - build up of nitrogenous products in the brain - altered awareness - cognitive impairment Complications - variceal bleed - internal bleeding ```

Question 38

What are the signs of ascites in liver disease?

Answer 38

``` Accumulation of fluid within the abdominal cavity Caused by - central hypovolaemia - reduced serum albumin - PHT and splenic artery vasodilation ```

Question 39

What are the signs of clotting abnormalities in liver disease?

Answer 39

Hepatocyte failure causes synthesis of defective clotting factors