Integumentary System & Body Membranes

Chapter Objectives: 1. Classify, compare the structure of and give examples of each type of body membrane 2. Describe the structure and function of the epidermis and dermis 3. List and briefly describe each accessory organ of the skin 4. List and discuss the three primary functions of the integumentary system 5. Classify burns and describe how to estimate the extent of a burn injury

Classification of Body Membranes Epithelial Membranes: Composed of epithelial tissue & underlying specialized connective tissue 1.Cutaneous …aka skin 2.Serous … aka saliva 3.Mucous … aka snot :P Connective Tissue Membranes: Contain no epithelial component 1.Synovial …line joint spaces between bones & bursae (sacs between moving body parts) →smooth, thick →secrete synovial fluid = for lubrication & reduce friction in joints

Serous Membranes… Composition: 1. Thin layer of simple squamous epithelium 2. Thin layer of connective tissue -forms supportive basement membrane Function: 1. body cavity lining and organ surface covering (single membrane w/ it’s surfaces named separately) *Parietal = name for body cavity lining *Visceral = name for serous membrane covering organs 2. Produce watery fluid to reduce friction & lubricate any organ contact Examples: 1. Thoracic cavity= called Pleura -so..Visceral Pleura=serous membranes covering the organs in thoracic cavity -Pleurisy= inflamed Pleura; very painful friction of lungs rubbing chest wall 2. Abdominal cavity= called Peritoneum -Peritonitis=inflamed serous membranes in abdominal cavity

Mucous Membranes… Location: -line body surfaces opening directly to the exterior -respiratory, digestive, urinary & reproductive tracts Composition: * epithelium varies with location & function -Esophagus: stratified squamous epithelium –to protect from rough particles -Lower Digestive Tract: simple columnar epithelium Function: -produce thick, slimy material- aka mucus (provide moisture) Mucocutaneous Junction = -skin and mucous membranes meet (eyelids, nasal opening) - lacks accessory glands, need mucous glands for moisture -common points of infection

The Skin *Primary organ of Integumentary System & largest body organ* Structure: →Epidermis → Dermis → Subcutaneous Appendages: → Hair → Receptors → Nails → Skin Glands -Sudoriferous gland (sweat) -Sebaceous gland (oil) Function: → Protection → Temperature Regulation → Sense organ activity Burns: →Surface area estimation →Classification

Structure: Epidermis … outtermost layer *Stratified Squamous Epithelium* Tightly Packed Arranged in layers {strata} Stratum Germinativum [innermost] →reproduces itself *self-repairing fxn! →new cells move toward surface as they specialize with… Keratin [ replaces cells cytoplasm]= tough, waterproof material for protection Stratum Corneum [outer layer of epidermis] →keratin filled, dead cells flake off *Melanocytes deep in epidermis- produce melanin → absorb harmful UV & give skin darker pigment → with less melanin color can change w/ blood flow or oxygen level changes Cyanosis: skin bluish gray with ↓blood O2 or ↓blood flow * Specialized Junctions hold epidermis together and attach to dermis Dermal-epidermal Junction= between thin epidermal layer and dermal layer below Blisters: result of weakened or destroyed junctions

Structure: Dermis *Thicker layer *mostly connective tissue -cells scattered with fibers between Upper Region: -Dermal Papillae -parallel rows of bumps (important in junction) -make finger/footprints unique Deeper Dermis: -Dense network of interlacing fibers -Specialized nerve network for sensory info Subcutaneous [aka. Hypodermis] -Layer of fat → insulation, provide stored energy, gives protection & shock absorption

Appendages Hair Follicles: required for growth Lanugo =hair of newborn Hair Papilla: where hair growth begins base of follicle Arrector Pili: small smooth involuntary muscle contraction makes goose bumps (ex. in cold/ or fear )

Appendages Receptors

Appendages Nails -produced by cells of epidermis -

Appendages Skin Glands *Sudoriferous gland (sweat) 1. Eccrine: Most numerous produce sweat 2. Apocrine Larger (growth starts at pupberty) Thicker secretions *Sebaceous gland (oil) - Lubrication for hair and skin Secretions increase during adolescence w/ hormone changes Secretions decrease late adulthood –forming wrinkles and cracks in skin

Function 1. Protection “First line of defense” Keratin prevents movement across skin barrier, keeps bacteria out and keeps fluid in Melanin protects from UV 2. Temperature Regulation Sweat Evaporation principle heat loss mechanism 3. Sense Organ Activity Touch, pressure, pain & hot/cold

Burns “Rule of Nines” Divides body into 11 areas-each 9% Recovery depends on total area involved and severity Classification of Burns 1 st Degree (sunburn) Minor discomfort, some reddening of skin, no blistering 2 nd Degree Severe pain, deep epidermal layers & upper dermis injured, blisters, swelling, fluid loss, scaring common 3 rd degree (full thickness burn) Complete destruction of epidermis and dermis, tissue death into subcutaneous tissue (can go to muscle or even bone), pain insensitive-nerve endings injured, serious fluid loss & risk of infection