Question

A portal system is a system in which

• A. A vein starts from an organ and ends up in heart.
• B. An artery breaks up in an organ and restarts by the
  union of its capillaries.
• C. The blood from the gut is brought into the kidney
  before it is poured into posterior vena cava.
• D. A vein breaks up in an organ into capillaries and restarts by their union as a new vein in the same organ.

Answer 1

Answer: (D)

A vein breaks up in an organ into capillaries and restarts by their union as a new vein in the same organ.

A portal venous system is a system in which a capillary bed pools into another capillary bed through veins, without first going through the heart. Both capillary beds and the blood vessels that connect them are considered part of the portal venous system.