The vein which is formed from the capillaries of an organ and terminates into capillaries in some other organ before entering the heart is called

• pulmonary vein

• coronary vein

• portal vein

• systemic vein

C.

portal vein

A portal vein is the vein which collects blood from one organ by a set of capillaries and distributes that blood into another organ through another set of capillaries instead of sending the blood into heart.

The pulmonary veins are the veins that transfer oxygenated blood from the lungs to the heart. The largest pulmonary veins are the four main pulmonary veins, two from each lung that drain into the left atrium of the heart.

The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium). It delivers less-oxygenated blood to the right atrium, as do the superior and inferior vena cavae.

The systemic venous system refers to veins that drain into the right atrium without passing through two vascular beds (i.e. they originate from a set of capillaries and do not pass through a second set of capillaries before reaching the right side of the heart).