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The integumentary system (skin) Roles: protection maintenance of normal body temperature storage (of fat) synthesis (of vitamin D) excretion (of salts, water and wastes in sweat) sensory perception. Tissues of the skin epidermis- straitified squamous epithelium
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The integumentary system (skin) Roles: protection maintenance of normal body temperature storage (of fat) synthesis (of vitamin D) excretion (of salts, water and wastes in sweat) sensory perception
Tissues of the skin epidermis- straitified squamous epithelium basement membrane dermis- largely connective tissue; many nerves and blood vessels; smooth muscle hypodermis- adipose tissue and more loose connective tissue
Epithelium deepest layer (stratum germinativum, or stratum basale)- rapidly dividing cells stem cells present outermost layer- stratum corneum dead, keratinized cells Melanocytes in stratum basale- produce pigment absorbs UV radiation; surround nucleus Cells vary in amount of melanin they produce
Epidermal cells make a precursor form of vitamin D Modified in liver and kidney Required for bone formation “Protection” includes immune protection Langerhans (dendritic) cells keratinocytes specialized T cells
Dermis- capillaries and nerves deeper layers are dense connective tissue; superficial layers are loose Subcutaneous layer loose connective and adipose tissue shock absorption, insulation, energy
Accessory structures Originate in epidermis (hair follicle), extend into dermis arrector pili muscle attached Hair is pigmented; determined by amount of melanin (Red hair requires a different pigment) Pigment production decreases with age Several specialized types of hair
Nails Nail bed overlaid by nail plate Nail growth originates from root; cells become keratinized Cuticle is formed from stratum corneum
Two types of exocrine glands Sebaceous- sebum (oil, wax) associated with hair follicles helps maintain pliability of skin Sweat glands apocrine (armpits, groin) merocrine (eccrine)- widely distributed important for maintaining body temperature
Aging and the integumentary system Declines in: Cell division in stratum basale Melanocyte production Glandular activity Hair follicle function Elastic fiber function in dermis Blood supply to skin Rate of repair
Problems of skin Lesions infections (bacterial, viral, fungal,parasitic) inflammatory reactions allergens Hyperkeratinization Tumors basal cell (stratum basale) squamous cell melanoma
Trauma abrasions, incisions, lacerations Repair inflammation scab formation fibroblast activity (scar formation) Burns- severity depends on depth of damage Rashes- so many causes!