Question

Choose the correct answer from the alternatives given.
A portal system is that in which:

• A. a vein starts from an organ and ends up in the heart
• B. a vein breaks up into a capillary network before returning the blood to the heart
• C. the blood from the gut is brought into the kidney before it is poured into the post caval vein
• D. an artery breaks up, in an organ, into capillaries and restarts their union as a new artery in the same organ

Answer 1

The correct option is B a vein breaks up into a capillary network before returning the blood to the heart

• Portal system can be defined as a part of the systemic circulation, in which blood draining from the capillary bed of one structure flows through larger vessels to supply the capillary bed of another structure, before returning to the heart.
  
• Simply, a system of blood vessels that begins and ends in capillaries is called portal system. Example: In hepatic portal vein (a part of the portal system), vein begins in a capillary of intestines and ends in another capillary of the liver.
  

So, the correct option is 'A vein breaks up into a capillary network before returning the blood to the heart'.