AWABS - Liver Physiology

Question 1

Liver anatomy

Answer 1

1.5-2 kg
Right and Left lobes divided by falciform ligament

Question 2

Blood flow received by liver

Answer 2

25% of cardiac output
1.5 L blood flow per minute

Question 3

Blood supply of liver

Answer 3

25% Hepatic artery (oxygen rich)
75% Hepatic portal vein (nutrient rich)

Question 4

Splanchnic circulation

Answer 4

Question 5

Functional divisions of liver

Answer 5

Question 6

Factors which increase hepatic blood flow

Answer 6

Supine position
Ingestion of food
Hypercapnia
Acute hepatitis
P450 enzyme inducers

Question 7

Factors which reduce hepatic blood flow

Answer 7

Upright position
PEEP / IPPV (reduced venous return)
Cirrhosis
Hypocarbia

Question 8

Functional units of the liver

Answer 8

Hepatic lobules
Hexagonal
Arranged around central vein which connects to hepatic veins
Cords of hepatocytes radiate out
At each corner is the portal triad

Question 9

Sinusoids

Answer 9

Question 10

Metabolic units of liver

Answer 10

Question 11

Functions of the liver

Answer 11

Synthesis
Metabolism
Storage
Catabolism and excretion
Immunological / Haematological
Reservoir

Question 12

Substances synthesised by liver

Answer 12

Proteins
Fats
Bile

Question 13

Substances metabolised by the liver

Answer 13

Glucose homeostasis and other absorbed nutrients

Question 14

Substances stored by liver

Answer 14

Glycogen
Vitamins
Iron
Copper

Question 15

Substances catabolised / excreted by liver

Answer 15

Drugs
Urea
Bilirubin

Question 16

Reservoir function of liver

Answer 16

450+ mls of blood

Question 17

Albumin synthesis rate by liver

Answer 17

200 mg/kg/day

Question 18

Some examples of proteins synthesised by liver

Answer 18

Albumin
Clotting factors (all except factor 8 produced in liver)
Acute phase proteins inc CRP

Question 19

Drug handling by liver

Answer 19

All substances absorbed in gut pass through liver via portal vein into the systemic circulation (1st pass)

Many also re-presented from systemic circulation (2nd pass)

Once drugs reach hepatocyte they are metabolised by SER

Question 20

Phase 1 reactions

Answer 20

Alteration if molecular structure
Involves oxidation or reduction
Resulting compounds are more polar or water soluble
Cytochrome P450 are main players in phase 1 metabolism

Question 21

What happens to metabolites after phase 1 reactions occur

Answer 21

After phase 1 the compound is either:
- Sufficiently water soluble and excreted
- Able to go into phase 2 metabolism
- Toxic and require further metabolism
- Bioactivated

Question 22

Phase 2 reactions

Answer 22

Attachment of ionised groups to the drug

Question 23

Methods of alterations in phase 1 and 2 reactions

Answer 23