How The Urine Is Formed
Blood enters the glomerular capillaries by the afferent arteriole and leave through an efferent arteriole. High hydrostatic pressure in the capillaries pushes the filtrate into the Bowman’s space. This filtrate contains water, glucose, salts, minerals, small amount of protein and waste products like urea and creatinine. About 180 liters (125ml/min known as GFR) of ultrafiltration is produced by all the glomeruli daily. This large amount of ultrafiltrate contains both waste and essential products.
As it passes through the tubules most of the essential substances and water is reabsorbed, so the final urine reaching the renal pelvis is only 1.5 to 2 liter in amount and mostly clear of essential substances needed for the human body.