Portal vein gives 75 per cent of flow, hepatic artery gives 50 per cent of oxygen
Expansion
- Portal vein - about 75 per cent of blood flow, but partly deoxygenated; delivers around half the oxygen
- Hepatic artery - about 25 per cent of flow, fully oxygenated; delivers the other half
Blood from both mixes in the sinusoids, flows past the hepatocytes towards the central vein, and leaves through the hepatic veins into the inferior vena cava.
The functional consequence is the basis of an important intervention. Because liver tumours derive their supply almost entirely from the hepatic artery while normal parenchyma is sustained by the portal vein, the artery can be selectively embolised, transarterial chemoembolisation - killing tumour while sparing normal liver.
It also explains zonal injury: zone 3 hepatocytes, furthest from the portal triad and nearest the central vein, are the least oxygenated and the first to die in ischaemic hepatitis or paracetamol toxicity.