The integumentary system (skin)

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The integumentary system (skin) Roles protectio
n maintenance of normal body temperature storage
(of fat) synthesis (of vitamin D) excretion
(of salts, water and wastes in sweat) sensory
perception
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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
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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
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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
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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
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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
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Nails Nail bed overlaid by nail plate Nail
growth originates from root cells
become keratinized Cuticle is formed from
stratum corneum
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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
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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
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Problems of skin Lesions infections (bacterial,
viral, fungal,parasitic) inflammatory
reactions allergens Hyperkeratinization Tumors
basal cell (stratum basale) squamous
cell melanoma
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Trauma abrasions, incisions, lacerations Repair
inflammation scab formation fibroblast
activity (scar formation) Burns- severity
depends on depth of damage Rashes- so many
causes!