The Integumentary System The skin (cutaneous membrane) and its accessory structures

General Functions of the Skin Regulation of body temperature –Describe the homeostatic mechanisms Protection as a physical barrier –Most importantly, what chemical does the skin keep in? –What materials do not pass through intact skin? –What materials may pass through intact skin? Why? Sensory receptors Excretion and absorption –small amounts salt, CO2, ammonia and urea are excreted Involved in the synthesis of vitamin D

Overview of Epidermis Stratified squamous epithelium Contains no blood vessels several strata (layers) of cells What is the origin of the upper layers of epidermal cells? Why is the structure and function of epidermal cells different in the different strata? aka Stratum germinativum

Layers (Strata) of the Epidermis

Dermis Connective tissue layer composed of collagen & elastic fibers, fibroblasts, macrophages & adipocytes Contains hair follicles, glands, nerves & blood vessels Major regions of dermis –papillary region –reticular region Describe the location of the following injections: subcutaneous (SQ), hypo- dermic, intradermal (ID), and intramuscular (IM). Differentiate between calluses and pressure (decubitus) ulcers.

Accessory Structures of Skin How are sweat glands and ceruminous glands similar? What is sebum? What is the relation- ship between hair, nails and the epidermis?

Photodamage Ultraviolet light (UVA and UVB) both damage the skin Acute overexposure causes sunburn DNA damage in epidermal cells can lead to skin cancer UVA produces oxygen free radicals that damage collagen and elastic fibers and lead to wrinkling of the skin

Skin Cancer 1 million cases diagnosed per year 3 common forms of skin cancer –basal cell carcinoma (rarely metastasize) –squamous cell carcinoma (may metastasize) –malignant melanomas (metastasize rapidly) most common cancer in young women arise from melanocytes ----life threatening key to treatment is early detection watch for changes in symmetry, border, color and size (A,B,C,D) risks factors include-- skin color, sun exposure, family history, age and immunological status