Purpose - To demonstrate how the epidermalcells are rubbed off.
Materials - bar of soap
sheet of paper course sandpaper
■ Hold the barof soap over the paper.
■ Gently rub thesoap against the sandpaper.
Results The outer surface of the soap baris rubbed off by the rough surface of the sandpaper.
Why? The outer layerof human skin, the epidermis, like the soap is constantly rubbed off, but unlike the soaphuman cells are replaced. We live in a world that constantly rubs, scrapes, grinds, cuts, and pushes against our skin. The outer layer is composed of deadcells that just fall off when touched. The body does not wear away as the soapdid because there is a constant replacement of these lost cells by the underlayer of cells. When cut, the cells grow back together. The epidermis isconstantly changing and repairing itself.