Human Body Project - Excretory System
Before building our excretory model, we experimented with dialysis tubing: (Left) red food coloring - didn't filter through except for a couple spare molecules, (Center) iodine - filtered through; and (Right) both iodine and red food coloring, mostly iodine and slight traces of red food coloring filtered through. We then used this concept to demonstrate how kidneys filter wastes in blood. The iodine represents the waste, which is selectively transported out of blood vessels that bring blood into the kidney. The slight traces of red food coloring that slightly leak out, which represent the non-waste blood that goes back to the heart and body, represents how some materials filtered out are still important (like water) and are later reabsorbed into the body during the last stages of reabsorption.