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The Integumentary System 5 Unit 1 Chapter 5 Integumentary System The Body Covering Includes: skin, nails & hairs Skin = cutaneous membrane Unit 1 • • • 5 • • • • Two main parts = Epidermis- surface epithelial layer Dermis -deeper connective tissue layer Deep dermis not part of the skin = subcutaneous layer or Hypodermis 5 Unit 1 Structure Figure 5.1 • • • • • 5 Keratinized stratified squamous epithelium 4 cell types: Keratinocytes Melanocytes Langerhans cells Merkel cells Unit 1 • Epidermis • • • • • • Keratinocytes 90% of epidermal cells 4-5 layers Produce keratin Protect skin Waterproof skin 5 Unit 1 Epidermal Cells Epidermal Cells Melanocytes - produce melanin Transfer pigment to keratinocytes 8% of epidermal cells Unit 1 • • • 5 Epidermal Cells • Langerhans Cells- immune response Merkel cells – sensory Include tactile disc and neuron = touch sensation Unit 1 • 5 Epidermal Layers • • • 5 Generally 4 strata (layers) Stratum basale –includes stem cells Stratum spinosum – 8-10 cell layer Cells beginning to look flattened Stratum granulosum –keratin Losing cell organelles and nuclei Include lamellar granules = waterproofing lipid • Stratum corneum – flattened dead cells Cells shed and are replaced from below- mostly keratin-filled Unit 1 • Skin Color • 5 Melanin- dark color Darkness depends on amount of melanin produced. gives some protection against UV • Carotene- yellow orange • Hemoglobin in blood- pink-red Depends on blood flow Unit 1 In stratum corneum and adipose layers- Accessory Structures Hair Skin glands Nails Unit 1 • • • 5 Hair • 5 Found on most skin surfaces Not on palmar surfaces of hand and fingers or plantar surfaces of feet Made of fused keratinized cells Consists of shaft & root Surrounded by hair follicle Base is bulb which includes growing matrix producing cells • • Nerves- hair root plexuses Muscle- arrector pili Unit 1 • • • Figure 5.3 Glands • • • • sebaceous gland- secrete oily sebum Connected to hair follicles sudoriferous or sweat gland Eccrine sweat gland Wide distribution- thermoregulation apocrine sweat gland Axilla, groin, areolae, beard Contain other cell material and produce pheromes Ceruminous Glands- external auditory canal Combine with sebum to produce earwax Unit 1 • 5 • • • • Plates of packed hard dead keratinized cells Nail body- major visible portion Free edge- part extending past finger or toe Root – part not visible 5 Unit 1 Nails Figure 5.4a Figure 5.4b • • • • • Temperature Regulation Protection Sensory reception Excretion & Absorption -small Vitamin D synthesis 5 Unit 1 Functions • • • • • • Adolescence- can develop acne Mostly dermis- visible ~ age 40 Loss of collagen fibers Loss of elasticity Loss of immune responses Decreased melanocyte functionsgray hair, blotches • Thinning 5 Unit 1 Aging
