THE INTEGUMENTARY SYSTEM

FUNCTIONS OF SKIN Regulates body

temp. Stores blood Protects body from

external env’t. Detects cutaneous

sensations Excretes and

absorbs substances Synthesizes vitamin

D

SKIN LAYERS: EPIDERMIS

Stratified squamous epithelium 90% have Keratin: a tough, fibrous protein

(protection) Granules: release a water-repellent sealant 8% have melanin: pigment that absorbs UV

light

Langerhans cells:

immune response, recognize invading microbes

Stratum basale: simple cuboidal. Stem cells divide to produce new layers above.

Outer layer is 30 layers of flattened, dead cells

Light blue - Langerhans cellDark blue- melanocyteBrown- stem cells

LOWER LAYERS Dermis: connective

tissue, elastic fibers. Blood vessels Nerve endings Hair follicles Sweat glands Oil glands Subcutaneous: fat,

collagen, elastic fibers

SKIN COLOR

Combination of melanin, carotene, and hemoglobin pigments.

# of melanocytes the same in everyone, but the amount of melanin differs.

Tanning: increased melanin production to absorb UV.

USING SKIN COLOR TO DIAGNOSE ILLNESS

Yellow skin/eyes- liver disease (jaundice)

No melanin - albinism Bluish nails- cyanosis Erythema-

inflammation, allergies

SKIN CANCER Cause: excessive

exposure to the sun. 1million cases per year in US, number increasing.

Basal cell: tumors in the stratum basale:78%

Squamous cell: 20%Tumors in stratum

spinosum of epidermis. Melanoma: arise from

melanocytes- life threatening. 1:75 chance lifetime risk.

Asymmetry

Border

Color

Diameter

BURNS

1st degree: epidermis only, no blisters

2nd degree: epidermis + dermis , blisters

3rd degree: destroys all layers of skin. Requires a skin graft.

Systemic effects: large loss of water, plasma, infection, reduced immune response.