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Integumentary System A.K.A.: Skin Chapter 6 Integumentary Overall Functions 1. 2. 3. 4. 5. Protect Underlying tissues & organs Excrete salts, water, & organic wastes (excretory organ) Maintain normal body temperature Synthesize vitamin D in epidermis Sensation of touch, pressure, pain, & temp. Integumentary Overview 1. 2. Main Structure: Cutaneous Membrane 1. Epidermis 2. Dermis Subcutaneous layer Accessory Structures Hair Follicles Exocrine Glands Sebaceous Sweat Nails Nerve Endings Skin Epidermal Layers:Stratified Squamous 1. 2. 3. Stratum Germinativum – Stratum Basale Mitosis Stratum Spinosum Some cells still divide Stratum Granulosum Keratin (protein): Day 1 Water resistant, durable (poor envmt for bacteria) also nails, hooves, horns, quills 4. 5. No more mitosis Stratum Lucidum: palms & soles only Stratum Corneum (superficial) Flattened, dead, keratinized cells Day 14 Shed after 2 wks Epidermal Layers Eyelid Palm & Sole Epidermal Functions 1. Vitamin D synthesis 2. 3. Stratum spinosum & germinativum UV light + steroid precursor Vitamin D Vitamin D Purpose: Needed for bones to absorb calcium Ricketts: bone disease Epidemic in inner city Protection/ Waterproof Protective Senses Skin Color: 2 Determinants Hemoglobin: Good O2 reddish tint 1. • More red, inflamed Less pale Cyanosis: sustained decr. O2 blue • Caused by extreme cold or cardiopulm. dz. • • 2. Skin Pigments Carotene: (carrots) 2. Melanin: • Melanocytes (germinativum & dermis), Melanocyte stimulating hormone (MSH)pituitary gland & Melatonin- pineal gland • Albino: can’t produce melanin 1. Cyanotic Foot Melanocytes Nerve Endings of Epidermis 1. 2. 3. 4. Free Nerve Endings: Pain & Temp. (epidermis & dermis) Merkel’s discs: static L.T. (epidermis) Meissner’s Corpuscles: dynamic L.T. (dermis) Pacinian Corpuscles: deep pressure & vibration (deeper tissue- subcutaneous) Dermis: 2 layers 1. Papillary Layer Areolar connective tissue Rich in capillaries & nerves Dermal papillae: extensions into epidermis Epidermal ridge (fingerprints) 2. Reticular Layer Dense irregular connective tissue Support, attachment, & allows flexibility Other Dermal Components & Functions Accessory Organs: hair, sweat & sebaceous glands Blood vessels Lymphatics: assists in tissue repair Nerve fibers: Sensory receptors & nerve fibers Controls blood flow & gland secretion rates Dermis: Wrinkles & Stretch Marks UV radiation & over stretched skin (pregnancy) Stretch elastin beyond limits Wrinkles & stretch marks Retin-A: vitamin A derivative Acne treatment incr. blood flow to incr. dermal repair & decr. wrinkles Subcutaneous Layer: Hypodermis Structure: loose connective tissue w/ abundant adipocytes In babies: more adipose WHY?? Adults: fat located differently in male, female Function: stabilizes skin, store energy, insulate Very elastic Good for med injection Slow, steady infusion No vital organs & limited # capillaries Accessory Structure: Hair Follicles Hairs found everywhere except palms, soles, lips, sides of fingers & toes Hair Structure: 1. Shaft: size, shape, and color of hair 2. Root: encloses matrix 3. Hair Follicle: Papilla: areolar tissue w/ capillaries Matrix: 4. 5. Medulla- division (inner layer) Cortex- begin keratinizing Cuticle- fully keratinized (outer layer) Arrector pili muscle: smooth muscles Nerve Root Plexus Hair Follicle Hair Types & Colors Types: 1. 2. 3. Vellus: fine, “peach fuzz” (most of body) Terminal: heavy, colored (head, eyebrows) Intermediate: in-between (legs & arms) Colors: 1. 2. 3. Determined by melanocytes at papilla Genetic Pigment production slows w/ age graying Exocrine: Sebaceous Glands 1. Sebaceous glands Holocrine glands Associated with hair follicle: secrete sebum Sebum: prevents drying & inhibits bacterial growth Shampoo: removes natural oilstiff, dry hair 2. Sebaceous Follicle 3. Secretes directly to epidermis face, back, chest Acne: (caused by hormone changes) Glands blocked, secretions accumulate inflammation bacterial infection Ceruminous Gland: cerumen (earwax)to protect inner ear Sebaceous Follicle & Gland Exocrine: Sweat Glands- 2 Types 1. 2. Apocrine Sweat Glands Secrete through hair Armpits & groin 1st secrete at puberty hormones Sexual state & identity + envmt for bacteria odor Merocrine Sweat Glands Widespread (palms/ soles) Secrete to skin surface Function: Cooling effect Apocrine Protection: dilute chem, wash away bacteria Merocrine Skin Local Control : Inflammation Epidermis= great protection Thick, keratinized cells Tight junctions b/w cells Sebaceous & sweat glands Avascular Papillary layer= bacterial heaven Once bacteria enters papillary layer inflamm response Mast cells initiate response Skin Local Control: Regeneration 1. Clot Formation: 1. Platelets & fibrin (scab) 2. Isolates area Creates network for new cell migration Division, Migration, & Phagocytosis: 1. Stratum germinativum 2. Divide & Migrate Granulation tissue: fibrin clot, fibroblasts, capillary network Macrophages Phagocytosis Regeneration (con’t) 3. Scar tissue (lots of collagen, little blood) 1. Fibroblasts 4. Contraction: 1. Platelets & epithelial cells 5. Damaged hair follicles, sweat & sebaceous glands replaced w/ scar tissue Pull wound together Clot dissolves Aging Integumentary System Temperature Control 1. 2. 3. Sweat Glands Cooling effect Muscles Mostly skeletal & arrector pili Blood Flow Superficial: heat transfer Deeper: maintain heat Application: Skin Cancer Basal cell carcinoma: Most common Malignant Germinativum (basale) layer Common Cause: UV radiation Metastasis rare Squamous Cell Carcinoma: 2nd most common Malignant Common cause: Metastasis UV radiation rare Melanoma: most dangerous & rare Malignant Cancerous melanocytes Common cause: UV radiation High Metastasis rate Diagnosis: ABCD Assymetry, Border, Color, Diameter Application: Burns & Skin Grafts 1. Partial 2. Thickness 3. Full Thickness Depth of Burn First degree Superficial epidermis Erythema, sunburn red, blisters, painful Heals in few days Second degree Down to germinativum & dermis red, moist, blisters, blanch with pressure Painful Accessory structures unaffected Minor if >15% body burned 3 weeks to heal Third degree Down to subcutaneous white, brown, black, or whit, dry Less painful WHY? Hard to heal if extensive through body skin graft may be needed Burns& Treatments Estimation of Burns •Rule of 9’s (p. 204) Skin Grafts Split- Thickness Epidermis Other Concerns: 1. Fluid & electrolyte balance 2. Thermoregulation 3. Infection 4. Contractures Full-Thickness Epidermis & Dermis Skin Flap All 3 layers Rule of 9’s Application: Decubitus Ulcer Decubitus Ulcer= Pressure Sore Most common: over bony areas (i.e. sacrum, heel) Cut off blood supply decrease nutrients & O2 to tissues Population most affected: Bed ridden Decreased sensation: diabetics (feet & hands), SCI Wheelchair bound Stages: I: reddening II: blister III: all 3 skin layers affected Risk of Infection IV: all 3 layers of skin & underlying tissues (muscle/ tendons/ bones) Prevention: positioning every 2 hours, weight shifts in wheelchair, cushioning/ supports Decubitus Ulcers