What is renal portal system ? Give its significance

Renal Portal System:
(a) Renal portal system carries blood from the posterior region of the body to kidneys. .
(b) It includes:
(i) Femoral arid sciatic veins.
Renal portal and pelvic veins.
© The renal portal vein receives the sciatic vein and
than proceeds forward towards the kidney to its side.
(d) The renal portal vein is joined by a dorso-lumbar vein from the dorso-lateral parts of the body wall and oviductal vein from the oviduct in the females, Significance of Renal Portal System : The renal
portal system collects the blood from the hide
parts of the body from which the urea and uric acid present in the blood are first got filtered in the
kidneys before the blood goes into post-caval and then to the heart.