Liver

Question 1

Function of liver:

Answer 1

Carbohydrate metabolism
Lipid metabolism
Protein and amino acid metabolism 
Synthesis of plasma proteins
Synthesis and secretion of bile
Drug and poison detoxification
Detoxification of amonia through urea cycle
Clearance of damaged cells,
proteins, hormones

Question 2

Hepatic artery:

Answer 2

Brings oxygenated blood to liver

Question 3

Hepatic portal vein :

Answer 3

Low in oxygen

Brings nutrients from gut, spleen, pancreas

Question 4

The liver….

Answer 4

Filters blood coming from digestive tract before passing it to rest of body…

…transforms and degrades substances and either returns them to the blood or excretes them into the bile

Question 5

How hepatocytes process compounds:

Answer 5

1) Uptake of substance from the blood across the basolateral membrane
2) Transport of substance within the hepatocyte
3) The substance may be modified by enzymes in the hepatocytes
4) The hepatocyte excretes the substance or its products into the bile across the apical membrane or back into the blood through the basolateral membrane

Question 6

Liver disease:

Answer 6

Hepatitis – inflammation of the liver triggers cell death by necrosis or apoptosis

Caused by…

• infection = hepatitis A, B, C, D, E viruses
• drugs = alcohol/paracetamol
• inherited = haemochromatosis, Wilson’s disease
• autoimmune = type 1 diabetes, sjogren’s syndrome
• hypertension, disbetes, obesity caused fatty liver

Question 7

Acute hepatitis:

Answer 7

Inflammatory process triggers cell death by necrosis or apoptosis
Most common cause is by viral infection (A, B, C, D or E)
Also caused by certain drugs or poisons e.g. ethanol

Question 8

Chronic hepatitis:

Answer 8

Viral infection (B, C or D)
Primary autoimmune disorders
Therapeutic drug-induced
Genetic disease e.g. Wilson’s disease

Question 9

Fulminant (dramatic and overall) hepatic failure:

Answer 9

Viral infection (A, B, D, yellow fever…)
Poisons and toxins e.g. death cap mushroom, ethanol, halothane, paracetamol
Ischaemia or hypoxia – vascular occlusion, circulatory failure, sepsis with shock

Question 10

Glycolysis =

Answer 10

Breakdown of glucose to pyruvate or lactose

Question 11

Gluconeogenesis =

Answer 11

Conversion of non glucose molecules to glucose

Question 12

Glycogenesis =

Answer 12

Glycogen formation

Question 13

Glycogenolysis =

Answer 13

Glycogen breakdown

Question 14

After eating:

Answer 14

Blood glucose increases
Increase insulin
Leads to glycogenesis

Question 15

Between meals:

Answer 15

Increase glucagon
Decrease insulin
Leads to glycogenolysis/gluconeogenesis
Glucose release into bloodstream

Question 16

Cholesterol:

Answer 16

Important component of call membranes

Precursor for bile acids

Precursor for steroid hormones

Question 17

Bile acids…

Answer 17

• are formed from cholesterol in the hepatocytes

- 90% of bile acids are recirculated by the enterohepatic circulation system

Question 18

Bile functions:

Answer 18

• Bile provides the sole excretory route for many solutes not excreted by the kidneys
• Secreted bile salts and acids are required for normal lipid digestion

Question 19

Jaundice:

Answer 19

Yellow skin and sclera

Result of build up of bilirubin in the blood

Caused by…

Increased destruction of red blood cells or haemolysis

Decrease in ability of hepatocytes to conjugate bilirubin to glucuronic acid

• defect in ability of hepatocyte to absorb bilirubin (Gilbert’s syndrome)
• inability to conjugate bilirubin because of a deficiency in glucuronyl transferase (Crigier-Najjar syndrome and neonatal hyperbilirubinaemia)
• problems in transferring bilirubin-glucuronate to the biliari canaliculi (Dubin-Johnson and Rotor’s syndromes)

Blockage of biliary ducts by gall stones or tumour

Question 20

Anti HBV (hepatitis B virus) approaches…

Answer 20

1) Entry inhibitors – impair viral propagation
2) DNA inhibitors/DNA destruction
3) Silencing – stop HBV RNA from forming
4) HBV RNA interference – knock down production of HBV proteins

Question 21

Cirrhosis:

Answer 21

Cirrhosis is an irreversible damage to normal liver structure where scar tissue replaces healthy cells

• hepatic injury
• fibrosis
• nodular regeneration

Cause… excess alcohol consumption or HBV/HCV

Question 22

Liver with chronic injury:

Answer 22

High density matrix containing fibril forming collagens.
Proliferating vitamin A deficient lipocytes
Loss of microvilli and fenestrations

Question 23

Cirrhosis increases vascular resistance in the liver

Answer 23

The increase in vascular resistance increases pressure and decreases blood flow through the hepatic portal vein. This results in formation of alternative return routes to the heart.

Question 24

Effects of portal hypertension :

Answer 24

oesophageal varices (prone to bleeding)
 enlarged spleen
 dilated abdominal veins
 ascites (abdominal fluid retention)
 haemarrhoides
 bile acid deficiency with malabsorption of fat and fat-soluble vitamins
 hyperglycaemia

Question 25

Effects of liver cell failure :

Answer 25

hypoglycaemia 
 coma
 jaundice
 ascites
 tendency to bleed (decreased prothrombin)
 anaemia
 ankle oedema
 fetor hepaticus (breath smells like a freshly opened corpse!)

Question 26

During a paracetamol overdose…

Answer 26

• major pathway is saturated
• increased proportion oxidized to NAPBQI and conjugated with glutathione
• glutathione reserves become exhausted
• build-up of the toxic non-conjugated NAPBQ = liver cell necrosis