BIOL 2160 Chapter : INTEGUMENTARY SYSTEM
Document Summary
The integumentary system is the largest organ in the body and accounts for 8- It must be tough to protect us but supple so that we can move and stretch. The epidermis is the outer layer of skin. The majority of cells (95%) are specialised epithelial cells called keratinocytes which produce a tough protein called keratin. There are five distinct sub-layers of cells that represent the different stages in the keratinisation process. New skin cells are produced at the basal membrane (deepest epidermal layer) pushing the older cells towards the surface. As the keratinocytes get older and migrate closer to the skin"s surface they change from being square- shaped to flat, they become engorged with keratin and eventually die, losing all of their internal structures. These overlapping, closely packed layers of keratinized cells form a permeable barrier and are able to withstand scuffs and scrapes.
