ACS_0221.jpg - INTEGUMENTARY SYSTEM(skin appendages...

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Unformatted text preview: INTEGUMENTARY SYSTEM (skin & appendages ) Functions : protects internal structures from damage . sensory information communication produces vitamins & hormones ( Vit D) maintains balance of fluids ( prevent dehydration ) . maintain homeostasis (regulation of body temp) . stores fat protection from UV radiation EPIDERMIS (superficial layer) outermost protective layer rmis made out of dead Keratinized epithelial cells (Stratified squamous cells) " can be divided into thick skin (5 layers) & thin skin (4layers) types of cells = Waxy protein that helps waterproof skin MIS Keratinocytes - synthesizes Keratin protein ( in skin, hair, nails) on the surface are mostly dead heratinocytes & filled with keratin gives structure, durability, waterproof the skin odermis Langerhans cells - signal to immune system of an infection (phagocytic macrophage ) ingest unwanted invaders - developement of antigen immunity . Basal cells - ininnermost layer of epidermis - constantly divide to produce new cells that are pushed upwards to layer above melanin from melanocytes are trans- -replace older heratinocytes Melanocytes - melanin producing cells ferred to keratinocytes . Merkel cells - deep in epidermis at epidermal- dermal boundary produces pigment that protect skin from harmful UV radiation -touch receptor cells ( combine with nerve endings for sensory ayers of epidermis : (sheds off ) Merkel discs receptors ) Stratum Corneum = toughest layer & top layer of dead Keratinocytes cells (basic protection from environmental threats ) 2 Stratum Lucidum = thin & flattened layer of dead skin (ONLY IN THICK SKIN) - pg. sole of foot & palm of hand 3 Stratum Granulosum = Keratin production occurs 4 Stratum Spinosum = moderately active in mitosis Stratum Basale: where keratinocytes are formed before moving up the surface of epidermis (Contains melanocytes ) where mitosis occurs (undergo division) DERMIS 1 papillary layer : thin outer layer with dermal papillae with epidermal ridges Underlying layer of connective tissues with blood vessels, nerve endings 2) reticular layer = thick laver of dense irregular connective Tissue fibroblast cells - generate connective tissues - makes up most of dermis blood vessels : transport Oz & nutrients to skin & remove waste products (also transport vit D from skin = body ) supply lymph (with woc) to fight microbes = lymph vessels . Eccrine sweat glands = regulate body temperature by releasing watery secretion that evaporates from skin (Cool down skin) Sebaceous (oil) glands = (armpit /groin area) apocrine secretion - contains cytoplasm from secreting cells & attract bacteria = body odor releases sebum = lubricates skin & prevent drying ( in hair follicles) Ly susceptible to clog & attract bacteria . Collagen = Structural protein holds muscle & organs together & gives strength Exocrine glands Elastin = provides elasticity & stretchy skin is glands that produce & secrete substances onto epithelial surface HYPODERMIS Sebaceous Glands - innermost layer & composed of fat & loose connective tissue holocrine glands => secrete Sebum . insulates the body sebum . cushion & protects internal organs & bones from injury -> oily mixture of lipids & proteins connected to hair follicles & secrete sebum thru hair pore = Adipose tissue inhibit water loss from skin stores excess energy as fat , which helps insulate the body & the burning of f sweat Glands outer layer Eccrine Gland Apocrine Grand not connected to hair follicle *oily solution secretion (superficial ) elevated body temp activation (armpits, groin, palm, feet ) blood & nutrient supply decrease (forehead, neck, back) Stress activation => secrete salty solution bacteria feed on apocrine =>body thermoregulation gland =odor (deeper) the cells die & dehydrate when they reach top layer inner layer skin...
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