Integumentary System The Skin!

Integumentary System Anatomy Epidermal layer Dermal layer Physiology Regulates body temperature Protects internal tissues Sensation – touch, temperature, pressure, pain Excretion – water, salts, heat Immunity Blood reservoir – many tiny blood vessels Makes vitamin D

Cross Section of Skin

Skin has 2 layers Epidermis– outer, thinner portion composed of epithelium Dermis – inner, thicker part composed of connective tissue

Epidermis Keratinized stratified squamous epithelium cells Keratinocytes – produce protein keratin – Keratin – fibrous protein for protection and waterproofing Melanocytes – produce melanin – Melanin – pigment for skin color and absorbs UV light

Epidermis – deep to superficial layers Thin skin – most of the body – Stratum basale (stratum germinativum) – Stratum spinosum – Stratum granulosum – Stratum corneum (thin layer) Thick skin – palms, soles of feet Stratum basale (stratum germinativum Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum (thick layer

Stratum Germinativum (basale) Basal (base) cell layer (germinal) undergoes continuous mitotic division Produces all the other layers Made up of stem cells – Simple cuboidal or columnar

Stratum spinosum When prepared, shrink to have thorn-like projections Have melanocytes and Langerhans cells – Help with skin immunity to microbes

Stratum granulosum Cell apoptosis occurs here Contains lamellar granules – provide waterproof sealant to skin Transition between alive layers and dead layers of skin

Stratum lucidum Consists of flattened, dead, clear keratinocytes

Stratum corneum Keratinization – accumulation of keratin by moving through epidermal layers Dead cells are sloughed off (shed) and replaced by newly dead cells from deeper layers Made up of dead stratified squamous cells Callus – abnormal thickening of stratum corneum

Dermis Composed of connective tissue Blood vessels, nerves, glands, hair follicles 2 regions – Papillary – Reticular

Papillary region Consists of areolar C.T with elastic fibers Dermal papillae – projections into the dermis create ridges: fingerprints Contain tactile receptors – corpuscles of touch – Nerves sensitive to touch Pacinian corpuscles – sensitive to pressure Free nerve endings – sensitive to temperature

Reticular region Made of connective tissue, mainly collagen and elastic fibers Also contains – Adipose tissue – Hair follicles – Nerves – Oil glands – Sweat glands

Skin color Genetically determined Melanin – brown-black pigment, number the same in all races; production of melanin differs Carotene – yellow-orange pigment Hemoglobin – reddish/pinkish tint in Caucasians

Skin Physiology Vitamin D Deficiency – Skin needs UV rays to initiate production of vitamin D – Vitamin D is turned into calcitrol which helps in absorption of calcium in intestines – Lack of vitamin D – leads to rickets or osteomalacia

Skin Physiology Regulates body temperature – Done with sweat glands (sudoriferous) – Water/salt comes to surface – As water evaporates, heat is taken away with the water – Eccrine – function when hot – Apocrine – function during stressful times

Skin Physiology Oil Glands (sebaceous) – Released onto shaft of hair – Goes to surface of skin to: Protect, lubricate, and waterproof skin Problem – Drainage becomes blocked – pimples – Production of sebum (oil) is controlled by sex hormones

Skin Physiology Ceruminous (wax) glands – Secrete wax into ear canal – Functions: Insect repellant Keeps eardrum flexible – Problem Excess ear wax can interfere with hearing

Hair

Hair and Hormones Hisutism – Higher than normal levels of androgen (hormone) cause excessive hair on lip, chin, chest, thighs, abdomen Male-pattern baldness – Androgen inhibits hair growth for genetically predisposed males

Skin Wound Healing Epidermal Wound Healing – near the surface (abrasion – scrape), 1 st /2 nd degree burns – Detached, basal cells migrate till they meet each other – Cell division fills in the space – No bleeding – Epidermal growth factor (EGF) – protein hormone that stimulates growth of dermal cells and fibroblasts

Epidermal Wound Healing

Skin Wound Healing Dermal (deep) Wound Healing 4 phases – Inflammatory phase – Migratory phase – Proliferative phase – Maturation phase Scar formation

DWH - Phases Inflammatory – clot forms (platelets) – WBC arrive for defense Migratory – clot becomes a scab by fibroblast production – Epithelial cells begin to regrow

DWH - Phases Proliferative – Epithelial cells grow beneath scab – Collagen fibers deposited – Tissue is reformed Maturation – Sloughing off of scab – Collagen fibers organize

DWH – What would I see between these 2 phases?

Skin Disorders Cancer Warts Burns

Skin Cancers Over 1 million diagnosed each year Arizonan’s have 3-7x more risk than people in other states 3 common types – Melanoma – Basal cell carcinoma – Squamous cell carcinoma

Melanoma Most dangerous form of skin cancer Appears as: – Change in existing mole – Small, dark multicolored spot with irregular borders, elevated or flat, bleed or form scab – Cluster of shiny, firm, dark bumps – Larger than a pencil eraser

Melanoma Benign – not cancerous Malignant - cancerous

Basal Cell Carcinoma Come from cells in stratum basale of epidermis Appear on sun-exposed skin as: – Pearly or flesh-colored oval bump with a rolled border, may develop into bleeding ulcer – Smooth red spot indented in center – Reddish, brown, or bluish black patch of skin on the chest or back

Basal Cell Carcinoma

Squamous Cell Carcinoma Arise from squamous cells of epidermis Arise from damaged tissue Appear on sun-exposed skin as: – A firm, reddish, wart-like bump that grows gradually – Flat spot that becomes a bleeding sore and won’t heal

Squamous Cell Carcinoma

Symptoms Any change in size, color, shape or texture of a mole or other skin growth Open or inflamed skin wound that won’t heal ABCD’S of melanoma – A – asymmetry – B – border – C – color – D – diameter

Burns 1 st, 2 nd, 3 rd degree Named according to severity 1 st degree – Least severe – Redness or discoloration – Swelling and pain – Usually overexposure to sun – Only epidermis is damaged

Burns 2 nd degree – Affect epidermis and dermis – May blister – Scarring may result – Most painful because nerves are intact but tissue is damaged – May involve loss of skin function

Burns 3 rd degree – Worst burn – May look white or charred – Extend through all skin layers – epidermis, dermis, subcutaneous layer – Severe to no pain depending on nerve damage – Requires skin grafts

Burns