The structure of the NEPHRON is described in the Nephron - Ultrafiltration and Selective Reabsorption.
The first stage of urine formation begins when blood enters the glomerulus through the afferent arteriole.Blood leaves the body and enters the bowman's capsule.The diameter of the afferent arteriole is larger than the efferent one, which makes it easier for fluid to leave the blood.The filtrate enters the tubule which is the primary site of reabsorption.Most of the water is reabsorbed by osmosis, while all the sugar is MzE MzEd by active transport.