t he i ntegumentary s ystem. f unctions of s kin regulates body temp. stores blood protects body...

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.