Question

In which of the following, both hepatic and renal portal systems are present?
A) Amphibians, Reptiles, Mammals
B) Reptiles, Aves, Mammals
C) Cyclostomes, Fishes, Amphibians
D) Fishes, Amphibians, Reptiles

Answer 1

Lower vertebrates have two portal systems which are the areas of the venous system that begin in capillaries in tissues and join to form veins, they are called the hepatic (liver) and renal (kidneys) portal systems.

Complete answer:

1. The hepatic portal system is a series of veins that carry blood from the capillaries of the stomach, intestine, spleen, and pancreas to capillaries in the liver. It is part of the body’s filtration system. Its main function is to deliver deoxygenated blood to the liver to be detoxified further before it returns to the heart.
2. The renal portal system is the system of veins in fish and amphibians taking blood from the region of the tail or hind limbs. It later combines to form a renal portal vein further, this vein goes into the kidney and divides into capillaries. Kidneys separate nitrogenous wastes from this blood.
   3)In the case of fishes, amphibians and reptiles both hepatic and renal portal systems are found. But in the case of mammals only hepatic portal systems are present.

Additional Information: Arteries and veins have been named according to the organ to which they supply blood. Metabolic waste is circulated in the blood, and if allowed to accumulate, can reach toxic levels, whereas kidneys are supplied with blood containing wastes via the renal arteries. The kidneys filter metabolic waste from the blood, passing it to urine to be excreted safely.

Hence, the correct answer is option D.

Note: The importance of hepatic portal system is to carry nutrients from the digestive tract to the liver after a meal to store and metabolize. Renal portal system’s function is to supply blood to renal tubules when glomerular filtration is absent or downregulated.