Circulation of blood through heart:

 It is of 3 types:

1) Pulmonary circulation:

 

This flow of blood from right ventricle to left auricle is called pulmonary circulation.

2) Systematic circulation:

This flow of blood from left ventricle to right auricle is called systematic circulation.

These both circulations through heart are commonly called double circulation of blood through heart, as blood passes twice through heart.

3) Portal circulation:

A vein – that collects blood from one organ by a set of capillaries & distributes to another organ by another set of capillaries, instead of heart, is called portal vein.  The flow of blood through portal vein to any organ other than heart is called portal circulation.