INTEGUMENTARY SYSTEM
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 Vessels65 Hairs & Hair Muscles78 Nerves78 Sensors for Heat13 Sensors for Cold160 Sensors for Pressure100 Sebaceous/Oil Glands1300 Nerve Endings19,500,000 Cells0.5 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
Skin Structures
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
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
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
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: 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
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