Phosphate naturally occurs in both rocks and other mineral deposits. Throughout the natural process of weathering, the rocks gradually release the phosphate and the phosphate ions which are soluble in water mineralize phosphate compounds breakdown.
The afferent arteriole collects blood from the glomerulus and extends o the renal tubule where it divides into capillaries that ramify the tubule. This blood is the collected by the venules that join into the renal vein which carries blood away from the kidneys. The filtrate in the collecting tubule becomes urine and trickles down into the collecting duct where it joins urine from other nephrons. The urine then flows into the pelvis via the urinary bladder through the ureter.