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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 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
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
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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
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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
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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
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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)
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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