In vertebrates, most of the fluid that ultimately exits the body as urine first enters the nephron tubules by the process of

The water and solutes the first enters the nephron tubules undergo a process just before it exits the body as a urine. This process is called filtration. It operates when 20 percent of the solution volume is filtered in the renal corpuscle at a given time. It is reportedly stated that there are around 180 liters of this fluid being filtered by the kidney every day.