They trace a path from the pharynx to the anus being absorbed all the nutrients is secreted in the stool, this is because the substance has no more nutrient to provide the body
They move in the path from the bloodstream into the tubules, which is in the backward direction of reabsorption. These substances are K+ ions, H+ ions, NH4+ ions, creatinine, urea, some hormones, and some drugs. They are concealed because they can pretend as a natural toxin to us if unnecessary amounts are stored in inside the body.
