Why do you think capillaries surround the long tubules of nephron?

The kidney's function in filtration. The renal tubules located with in the kidney's and also known as nephrons, are the functioning units of the kidney's. Blood carries nutrients and waste. The renal tubules are surrounded by a capillary network so the blood can expel the waste material that is collects from the body. the renal tubules also replace nutrients and water that is still needed back into the capillaries.