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The Integumentary System
an organ within the integumentary system
composed of skin + accessory organs (ex. nails, hair, glands, nerve endings, sensory receptors)
deepest layer, actively mitotic
slightly mitotic, in conjunction with the stratum basale, referred to as the stratum germinativum; synthesis of keratin
present only in the thickest skin
20-30 layers of flattened, keratinized dead cells. closest to surface, most protective layer
loose connective tissue directly underlying the epidermis
due to the pulling of elastic fibers in the papillary layer
dense irregular connective tissue underlying the papillary layer (stretch marks)
loose connective tissue and adipose tissue interlaced with blood vessels (ex. hypodermis) (women 8% thicker than men)
subcutaneous blood flow
pigment acquired through the diet; thicker stratum corneum, primarily found in people of east asia
Melanin, produced by melanocytes found in the stratum basale; light to dark coloration
small, isolated patches of highly concentrated melanin secretion
Dark skin tones
serve to protect against cell damage due to excessive uv radiation; also more susceptible to damage by extreme cold
melanocytes respond to increased amounts of uv radiation by producing more melanin
necessary for proper bone growth; a deficiency results in rickets in children and osteomalacia in adults
Skin color differences are primarily due to..
amount of melanin produced and its distribution
approximately everyone has the same number
yellowish pigment acquired through the diet