Question

The most important anatomical/physiological feature optimizing the role of the liver as an interceptor of xenobiotics is:

a: Proximity to the stomach

b: Production of bile as an emulsifier

c: Circulatory links to the lungs

d: The portal circulatory system

Answer 1

Answer is OPTION D- THE PORTAL CIRCULATORY SYSTEM

EXPLANATION- The hepatic portal system aka the portal circulatory system of the liver is the venous system that returns blood from the digestive tract and slpeen to the liver, this blood is rich in what ever the substances stomach has absorbed, this blood directly goes to the liver even before it reaches heart to circulate throughout the body.

The liver when gets this blood from the stomach, the emzymes in the liiver called the "CYTOCHROME" enzymes of various types metabolise the xenobiotics as to make it into lesser toxic forms and convert it into more water soluable forms as to make it easily eliminated by the kidneys.

That is insimpler terms, the absorbed substances from the stomach directly go to the liver to get them detoxified first by the liver enzymes.

(examples of cytochrome enzymes are- CYP3A4, CYP5A etc. they are hundereds of types of enzymes in the liver to metabolise the xenobiotics.)

for example, warfarin is metabolised in the liver by the most common enzyme called CYP450. into other non toxic metabolites.