Kidney
Excrete waste products i.e urea
Regulate water potential of blood
Blood passing capillaries in the cortex are filtered, substances go into long tubules- ultrafiltration
Glucose and water are reabsorbed back into the blood- selective reabsorption
Ultrafiltration
Urea, salt, water and glucose, etc., is extracted from the blood in the kidney.
Blood passing the top of the nephron is under high pressure