The Integumentary system consists of the skin and its accesory structures and the The two major layers of the skin are the outer epidermis andthe inner dermis.Epidermis- made of stratified squamous epithelium; cells called keratinocytes.1. Stratum Germanitivum- the inner most layer where mitosis takes place; new cellsproduce keratin and die as they are pushed to the surface.2. Stratum Corneum- the outermost layers of dead cells; keratin prevents loss and entry ofwater and resists entry of pathogens and chemicals. 3. Langerhans Cells- phagocytize foreign material and stimulate an immune response bylymphocytes.4. Melanocytes- in the lower epidermis, produce melanin. UV rays stimulate melaninproduction; melanin prevents further exposure to the stratum germanitivum to UV rays bydarkening the skin. Dermis- made of irregular fibrous tissue; collagen provides strength, and elastinprovides elasticity; capillaries in the papillary layer nourish the stratumgermanitivum.1. Hair Follicles- mitosis takes place in the hair root; new cells produce keratin,die, andbecome the hair shaft. Hair of the scalp provides insulation from cold for the head;eyelashes keep dust out eyes; nostril hairs keep dust out of the nasal cavities.2. Nail Follicles- at the ends of the fingers and the toes; mitosis takes place in the nail root;the nail itself if dead, keratinized cells. Nails protect the ends of the fingers and the toesenable the fingers to pick up small objects. 3. Receptors- detect changes in the skin: touch, pressure, heat, cold, and pain; provideinformation about the external enviroment that indicates appropriate responses; sensitivityof the skin depends on the number of receptors present. 4. Sebaceous Glands- secrete sebum into hair follicles or to the skin surface; sebumprevents the drying of skin and hair. 5. Ceruminous Glands- secrete cerumen in the ear canals; prevents drying of the eardrum....
