Photomicrograph of a sectioned sebaceous gland 220x Sebaceous gland duct Hair

Photomicrograph of a sectioned sebaceous gland 220x

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Photomicrograph of a sectioned sebaceous gland (220x) Sebaceous gland duct Hair in hair follicle secretory cells Dermal connective tissue Sebaceous gland Sweat pore Eccrine gland
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Chapter 5. The Integumentary System Skin Epidermis Dermis Appendages Sweat glands - eccrine, apocrine, Oil glands - Hair, Nail Integumentary system functions Integumentary system
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Hair Functions- protection alerting the body to presence of insects on the skin guarding the scalp against physical trauma, heat loss, and sunlight Distribution entire surface except palms, soles, lips, nipples, and portions of external genitalia Consists of dead keratinized cells Contains hard keratin; more durable than soft keratin of skin Hair pigments: melanins (yellow, rust brown, black) Gray/white hair: decreased melanin production, increased air bubbles in shaft Hair shaft
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Hair Follicle Extends from the epidermal surface into dermis Two-layered wall: outer connective tissue root sheath, inner epithelial root sheath Hair bulb: expanded deep end Hair follicle receptor (root hair plexus) . sensory nerve endings around each hair bulb --- stimulated by bending a hair Arrector pili-smooth muscle smooth muscle attached to follicle responsible for “goose bumps” Hair shaft • Arrector pili muscle Sebaceous gland Hair follicle Hair root Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb : formed by infolding of epidermis, produce hair
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Photomicrograph of a cross section of a hair and hair follicle (250x) • Connective tissue root sheath Follicle wall • Cuticle • Glassy membrane • Cortex • Medulla • Internal epithelial root sheath • External epithelial root sheath Hair Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb
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Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb Internal epithelial root sheath External epithelial root sheath Connective tissue root sheath Follicle wall Hair matrix Melanocyte Hair papilla Subcutaneous adipose tissue Medulla Cortex Cuticle Glassy membrane Hair root
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Structure of a Nail Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes Later al nail fold Lun ule Nail mat rix Root of nail Proxi mal nail fold Hyponyc hium Nail bed Phalanx (bone of fingertip) Eponych ium (cuticle) Bod y of nail Free edge of nail (a ) ( b )
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Integumentary System Functions 1. Protection —three types of barriers Chemical Low pH secretions & defensins retard bacterial activity Physical/mechanical Keratin and glycolipids block water & water-soluble substances Limited penetration of skin by lipid-soluble substances, plant oleoresins (e.g., poison ivy), organic solvents, salts of heavy metals, some drugs Biological cells, macrophages antimicrobial peptide by corneum also sebaceous gland
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