Question

A portal system is that in which

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

In the circulatory system of animals, a portal venous system occurs when 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.

Examples of such systems include the hepatic portal system, the hypophyseal portal system and (in non-mammals) the renal portal system.

The functional significance of such a system is that it transports products of one region directly to another region in relatively high concentrations.

Therefore, the correct answer is option D.