integumentary system
DESCRIPTION
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Integumentary system
The integumentary systemThe skin and all its derivatives
E.g. Nails, hair, glandsProvides external protection
Fxns of the Integumentary systemProtection
Skin secretionsMelanin
Physical/mechanical barriersBiological barriers
E.g. DNA
Body temperature regulationCutaneous sensationMetabolic fxns
Synthesis of Vitamin DBlood reservoirExcretion
CharacteristicsCovers the entire body Accounts for about 7% of total body weight Pliable, yet durable Thickness: 1.5 to 4.0 mm Composed of the epidermis and dermis
Skin derivativesOriginates from the epidermis
Nails The nail matrix contains rapidly dividing cells that eventually
become dead and keratinized Hardened nails protect the delicate tissues of the fingers and toes
Hair follicles and hair Hair produced the hair follicles in the dermal layer of the skin
Hair is composed mainly of dead, keratinized cells A strand of hair is composed of three layers:
Medulla – the innermost layer Cortex – surrounds the medulla Cuticle – provides strength and maintains the structure of the
inner layers Hair color is determined by the pigment melanin produced by
melanocytes at the base of the hair follicle
Sweat glands Eccrine sweat glands
Found on the palms, soles, and forehead Secretes sweat
Sweat is composed of mainly water and salts Sweat is acidic and slows microbial growth on the skin
Apocrine sweat glands Found in the anogenital and axillary (armpit) regions Secretion contains the same components of true sweat plus fatty substances and
proteins Produces “body odor”
Ceruminous glands – produce wax Wax deters insects and blocks the entry of foreign material into the ear canal
Mammary gland – specialized sweat glands that secrete milk Sebaceous (oil) glands
Found all over the body except on the palms and soles Produce oil (sebum)
Sebum softens and lubricates the hair and skin; waterproofs the hair and skin