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The Integumentary System Chapter 36.3 • Organs are two or more tissues which together perform a specialized function. • Epithelial membranes are thin structures that usually contain both epithelial and connective tissue. • Mucous membranes – Line cavities that open to the exterior – Layer of epithelium over connective tissue; epithelium varies with location – Tight junctions and goblet cells • Cutaneous membrane is the skin – the major organ of the integumentary system • Integumentary system is the skin and the organs derived from it (hair, glands, nails) • One of the largest organs – 2 square meters; 10-11 lbs. – Largest sense organ in the body • The study of the skin is Dermatology Functions: 1. Regulation of body temperature – Cellular metabolism produces heat as a waste product . – High temperature • Dilate surface blood vessels • Sweating – Low temperature • Surface vessels constrict • shivering 2. Protection physical abrasion dehydration ultraviolet radiation 3. Sensation touch vibration pain temperature 4. Excretion 5. Immunity/ Resistance 6. Blood Reservoir 8-10 % in a resting adult 7. Synthesis of vitamin D uv light aids absorption of calcium Anatomy • Epidermis Skin • Dermis • Subcutaneous layer or hypodermis Dermis • Connective tissue layer • Collagen and elastic fibers, nerves, blood vessels, muscle fibers, adipose cells, hair follicles and glands. Accessory organs or epidermal derivatives • Hairs – Epidermal growths that function in protection – Shaft, root, and folllicle – Sebaceous glands, arrector pili muscle, and hair root plexus (touch) – Hair growth and replacement have a cyclical pattern – ‘male-pattern’ baldness Nails • Plates of highly packed, keratinized cells • Protection, scratching, & manipulation • Formed by cells in nail bed called the matrix ( in area of lunula) • 1 mm / week • Eponychium - cuticle Skin Glands • Sebaceous (oil) glands – Usually connected to hair follicles – Holocrine glands – Fats, cholesterol, proteins, salts, and cell debris – Moistens hair and waterproofs skin Skin color • Genetic factors – Same number of melanocytes – Albinism • Environmental factors – Uv light or x-rays Wound healing • Inflammation – Blood vessels dilate and become permeable • Heat, redness, swelling and pain • Shallow cuts – Epithelial cells migrate – Contact inhibition Deeper wounds • Inflammatory phase – Fibrin forms clot • Migratory phase – Fibroblasts make granulation tissue • Proliferative phase • Maturation phase • Scars – hypertrophic scar – keloid Burns • First degree or partial thickness burn – Only epidermis is damaged – Erythema, mild edema, surface layer shed – Healing – a few days to two weeks – No scarring • Second degree- deep partial-layer burn – Destroys epidermis – Blisters form – Healing depends on survival of accessory organs – No scars unless infected • Third degree or full-thickness burn – Destroys epidermis, dermis and accessory organs of the skin – Healing occurs from margins inward – Skin grafting may be needed • Autograft • Homograft • Rule of Nines