INTEGUMENTARY SYSTEM Comes from the word integumentum = outer covering (latin)

Skin – Did you know? The largest organ of the body - 21 square feet; 4 Kg/9 lbs – 15% of total body weight Varies in thickness from 1/50 inch (0.5 mm) in the eyelids to 1/4 inch (6.3 mm) in the soles of the feet Terms “derma” and “cutaneous” refer to the skin

One Square Inch 20 Blood Vessels 65 Hairs & Hair Muscles 78 Nerves 78 Sensors for Heat 13 Sensors for Cold 160 Sensors for Pressure 100 Sebaceous/Oil Glands 1300 Nerve Endings 19,500,000 Cells 0.5 Million Cells Dying & Being Replaced

Structure and Function Integumentary system is composed of the skin and accessory structures – hair, nails and glands Functions of the integumentary system Protection – barrier to ultraviolet rays, microbes, dirt, chemicals; shock absorber Sensory perception – pain, pressure, temperature and touch Temperature Regulation: blood vessels near surface constrict or dilate Storage – fat, glucose, water, vitamins, and salts. Water Balance: prevents loss of water and absorption (our wet suit) Waste Excretion (eliminates oil, salt, water, CO2 etc) Production – Vitamin D Protects the other body systems from injury and infection Helps the body maintain homeostasis by regulating temperature Radiation – transfer heat to cooler surface Conduction – direct transfer to objects Convection: transfer from skin by air Evaporation of perspiration retaining body fluids, and eliminating wastes (the skin waterproofs the body to prevent fluid loss) Sensory reception – major receptor for touch Helps synthesize vitamin D from the sun’s ultraviolet light – needed for bone growth

Skin Structures Related structures include sebaceous glands (oil glands), sweat glands, hair and nails Ref: Gerdin, J. Health Careers Today, 3rd edition, 2003, Mosby

Layers of Skin Epidermis: Most Superficial Dermis: Tough, Leathery Fibrous Connective Tissue; Only Part That is Vascularized Subcutaneous(Hypodermis): Superficial Fascia; Mostly Fat (Insulate & Absorb Shock); Anchors Skin to Underlying Structures Epidermis Outermost layer of the skin that is composed of a surface of dead cells with an underlying layer of living cells; complete regeneration approx 35 days Dermis Called the “true” skin; contains the blood and lymph vessels, nerves, involuntary muscles, sweat and oil glands, and hair follicles “machine room” of flesh Subcutaneous fascia or hypodermis The innermost layer; made up of elastic and fibrous connective tissue and adipose tissue; connect skin to muscle

Accessory Organs of the Skin Hair Nails Sweat Glands Sebaceous Glands

Hair and Hair Follicles Skin has hair in all areas except the soles of the feet and palms of the hands Hair serves to block foreign particles from entering the body and helps retain heat Hair fibers are rod like structures composed of tightly fused dead protein cells filled with hair keratin The visible portion is called the shaft The hair follicle are the sacs that hold the root of hair fibers. The erector muscles are tiny muscle fibers that cause the hair to stand erect. Goose bumps reduce heat loss Keratin – fibrous, water repellent protein. Soft keratin is a primary component of the epidermis while hard keratin is found in the hair and nails Anterior pilli = erector muscles are tiny muscle fibers attached to the hair follicles that cause the hair to stand erect. In response to cold or fright, muscles contract causing raised areas of skin = goose bumps. Action prevents heat loss

Nails Nails composed of dead, keratinized, epidermal epithelial cells that grow under the lunula (white portion of the nailbed) Cells that form the nail bed are linked together and form the nail. Nail is replaced if nail bed is OK

Nail = unguis – each nail consist of: The nail body = made up of hard, keratinized plates of epidermal cells The nail bed = joins the nail body to the underlying connective tissue and nourishes the nail. The blood vessels give the nail its characteristic pink color The cuticle = narrow band of epidermis attached to the surface of the nail just in front of the root The Lunula = a pale, half moon-shaped region at the nail root Root = fastens the nail to the finger or toe by fitting into a groove in the skin The free edge = potion of the nail not attached to the nail bed, extends beyond the finger or toe tip

Glands Function is to help regulate the body temperature and excrete body wastes Three types of glands in the skin Sebaceous glands (oil) – usually open to hair follicles; produce sebum (oil that is antibacterial and antifungal); plugged = pimple Sudoriferous glands (sweat) – coiled tubes that extend thru dermis and open on the surface of the skin at the pores Ceruminous glands – produce cerumen (earwax)

ASSESSMENT Color/pigmentation: Temperature Moisture/Turgor Melanin: only pigment made in the skin; yellowish to red-brown to black; synthesis depends on enzyme in melanocytes; racial differences in the amt of melanin made; local accumulations = freckles Carotene: yellow to orange hue esp. visible on palms and soles Abnormal colors: erythema, cyanosis, pallor, jaundice, etc Temperature Moisture/Turgor Texture/thickness

Medical Specialties Related to Integumentary System Dermatologist – diagnoses and treats disorders of the skin Cosmetic/Plastic surgeon – specializes in the surgical restoration and reconstruction of body structures. (Plastic refers to plasty = surgical repair)

Diagnostic Procedures for Skin

Direct Examination Good lighting required Distribution of lesions (local or general) When lesions are most bothersome Changes in patient’s way of living Wood’s light (for ringworm) Microscopic exam for scales or fungi

Sensitivity Tests Patch test Percutaneous test (scratch test) Intradermal test

Biopsy Dermal punch Examined by histologist or pathologist

CLASSIFICATION OF SKIN LESIONS Macule - Flat, discolored spot or patch of skin (i.e., freckles) Papule - Elevated, solid lesion of the skin Nodule - Circumscribed, elevated and mainly solid lesion which is located deep in the dermis or subcutaneous tissue Wheal- Smooth, slightly elevated, swollen area; solid elevation from an accumulation of fluid; usually redder or paler than the surrounding area and accompanied by itching (e.g., insect bite) Plaque- Elevated, disc-shaped lesion Crust – a collection of dried serum and cellular debris (SCAB) Nevi – also known as moles Scale – flaking or dry patch made up of excess dead epidermal cells Macule - Flat, discolored spot or patch of skin (example: freckle) Papule - Elevated, solid lesion of the skin (example: wart) Nodule - Circumscribed, elevated and mainly solid lesion which is located deep in the dermis or subcutaneous tissue (example: fibroma) Vesicle - Sharply circumscribed, fluid containing lesion that is elevated (example: varicella)

CLASSIFICATION OF SKIN LESIONS (continued) Contusion – injury that does not break the skin; characterized by swelling, discoloration, and pain Ecchymosis = bruise; caused by bleeding within the skin Petechiae = small pinpoint hemorrhages