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