<p>Integumentary system: (SKIN) Functions 1. Physical protection from outside environment (skin) 2. Regulation of body temperature sweat gland, oils (antibacterial agents) 3. Excretion 4. Nutrition synthesizes vitamin D from sun light 5. Sensation touch 6. Coordinates immune defense</p><p>2 major components of the skin 1. Cutaneous membrane a. Dermis b. Epidermis</p><p>2. Accessory structures a. Hair b. Nails c. Glands</p><p>Epithelial, connective, muscle, nervous all found in the integument</p><p>Epidermis: Consists of keratinized stratified squamous epithelia 4 cell types- 1. Keratinocyte produces keratin (most abundant) water proofs 2. Melanocyte produces melanin (pigments) absorbs UV light 3. Merkel cells sensory nerve ending receptors 4. Langerhans cells phagocytic cells, against pathogens & epidermis cancer cells</p><p>Layers of epidermis: 1. Stratum germinativum (basal) -Attaches to basal lamina of basement membrane -Large stem cells or basal cells -Contain Melanocyte -Lack hair but have Merkel cells 2. Stratum spinosum (spiny) - Stem cells differentiation into keratinocyte - Several Layers thick - Keratinocyte tie together by desmosomes & tonofibrils - Langerhans cells present 3. Stratum granulosum (granular) - Keratinocyte displace from spinosum layer - Produce keratinocyte surrounds keratin filaments & keratinocyte begin to die 4. Stratum lucidum (clear)</p><p>- Found in thick skin of palms and soles of feet may or may not be present 5. Stratum Corneum - 15 to 30 layers thick flat dead cells - Cornified large amounts of keratin - Continually shed and replaced - Serves as a barrier against light and heat - Protection against bacteria & chemicals</p><p>Epidermis ridges- deep layers of epidermis extending into dermis</p><p>Dermal papillae- projection from dermis expanding into epidermis (fingerprints)</p><p>Skin color - Due to blood supply (blush) - Pigments (carotene, melanin) - Pink - capillaries</p><p>Dermis: - Lies deep to epidermis (2 Layers) a. Papillary layer contains capillaries, nerves, loose connective tissue b. Reticular layer blood vessels, hair, follicles, sebaceous glands, dense connective tissue</p><p>Nerve receptors of the skin: 1. Meissner’s corpuscles touch 2. Ruffini corpuscles stretching 3. Pacinian corpuscles deep pressure & vibration</p><p>Subcutaneous: - Hypodermis/superficial fascia - Loose connective tissue adipose - Not a “true” part of integument - Large arteries & veins - Baby fat</p><p>Accessory structures: - Hair, hair follicles, sebaceous, nails, sweat glands 1. Hair/ follicles protection, deep in dermis - Hair papilla root = shaft (hair) - Hair bulb, surrounds papilla</p><p>Arrector pili muscle - Smooth muscle, surrounds hair - Follicle makes hair stand up - Works with sebaceous glands in excreting sebum</p><p>Root hair plexus: - Sensory nerves, surrounding the base of each hair follicle Glands: - Sebaceous glands  produces sebum for protection and lubrication - Sweat glands a. Apocrine- axilla, aereola & groin = pheromones b. Eccrine/merocrine8i widely distributed produce sweat</p><p>Other Integument glands 1. Mammary 2. Ceruminous ear wax produces cerumen; extern, audit canal</p><p>Nails: a. Nail body- visible part b. Nail bed- under the body c. Nail root- nail production occurs</p><p>The Skin throughout Life</p><p>1. most skin aging is cause by the sun and is called photoaging. UV induced activation of enzymes which degrade collagen 2. liver spots 3. decline in collagen</p>