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The Integumentary System: Skin

The Integumentary System: Skin. Integumentary System. The Body Covering (Fun Fact! Largest organ of the body) Includes: Skin, Nails & Hairs Skin A.K.A. C utaneous Membrane Functions : Body Temperature R egulation : Sweating at surface and adjusting blood flow in dermis.

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The Integumentary System: Skin

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  1. The Integumentary System: Skin

  2. Integumentary System • The Body Covering (Fun Fact! Largest organ of the body) • Includes: Skin, Nails & Hairs • Skin A.K.A. Cutaneous Membrane • Functions: • Body Temperature Regulation: Sweating at surface and adjusting blood flow in dermis. • Protection: Keratin protects from microbes, abrasions, heat and chemicals, lipids slow evaporation of water, melanin protects from UV rays. • Cutaneous Sensations: Sensory input/output • Excretion and Absorption: Eliminates substances, passage of materials into body cells (drugs) • Synthesis of Vitamin D: UV light activates creation of Vit D

  3. Structure • Skin is divided into two main parts: • Epidermis(epi = above) Surface epithelial layer • Dermis: Deeper connective tissue layer • Subcutaneous Layer Deep dermis not part of the skin. • Fibers from dermis anchor skin to this layer which then allows for attachment to other tissue and/or organs.

  4. Epidermis • Made of keratinized stratified squamous epithelium • Capable of regeneration (new cells ~ q4 weeks) • 4 cell types: • Keratinocytes: 90% of epidermal cells, 4 – 5 layers, produces keratin (rough fibrous protein that protects skin), waterproofs skin. • Melanocytes: 8% of epidermal cells, produce the pigment melanin, transfer melanin to keratinocytes, susceptible to UV light damage. • Langerhanscells: Produce immune response against pathogens entering skin. • Merkelcells: Detect touch/sensory sensations.

  5. Dermis • Consists of two distinct regions: • The superficial part is composed of areolar connective tissue. • The deeper partis composed of dense irregular connective tissue. • Attaches to the subcutaneous layer. • The outer layer contains nerve endings for touch, thermal sensations, pain, tickling, and itching.

  6. Skin Color • Skin color is due to the melaninin the epidermis, carotene in the dermis, and hemoglobin in the capillaries of the dermis. • Melanin (Brown-Black pigment) • Darkness depends on amount of melanin produced. • Gives some protection against UV • Malignant melanoma, (cancer of the melanocytes), is a particularly serious skin cancer. Liver or age spots, are non-cancerous clusters of melanin. • Carotene (Yellow-Orange pigment) • In deeper skin and adipose layers • Hemoglobin (Pink-Red pigment) • Found in blood • Depends on blood flow

  7. Review: Skin • What are the 5 functions of skin? • What are the two main parts of skin called? • What 4 cells make up the superficial/thinner part of the skin? • What is the function of the subcutaneous layer? • What specific type of epithelial cells make up the epidermis? • Which skin layer contains nerve endings? • Which pigments contribute to which skin color? • The shade of your skin depends on which factors? • What are the characteristics and functions of keratinocytes?

  8. The Integumentary System: Accessory Structures of the Skin

  9. Hair • Function: Protection • Found: On most skin surfaces • Not on palmar surfaces of hand and fingers or plantar surfaces of feet • Composition: • Keratinized cells • Shaft: Mostly above ground • Root: Below surface • Surrounded by hair follicle • Bulb: Base of hair follicle includes matrixproducing cells and blood vessels. • Nerves: Hair root plexuses • Sensitive to touch • Muscle (Smooth): Arrectorpili • Contraction causes goose bumps Hair Shaft Sebaceous Gland Hair Root Hair Root Plexus Arrector pili muscle Bulb Apocrine sweat gland

  10. Glands • SebaceousGlands: Secrete oily sebum • Protects skin from drying out and bacteria • Connected to hair follicles • Sudoriferous(soo-dor-IF-er-us) Glands: Secrete sweat • Eccrine are widely distributed, & aid in thermoregulation • Apocrineare found in the axilla, groin, areolae, beard • Ceruminous(se-ROO-mi-nus)Glands: Secrete wax • External auditory canal • Combine with sebum to produce earwax • Provide barrier against foreign bodies

  11. Nails • Function: Help us grasp, manipulate objects, protect ends of digits, scratching • Composition: Plates of packed keratinized cells of the epidermis. • Nail body: Visible portion • Free edge: Part extending past digit • Root: Part not visible • Growth: 1 mm per WEEK! Slows within 2nd / 3rd decade Becomes brittle with age Free Edge Nail Body Root

  12. Review: Accessories • What are the 5 functions of hair? • What protein is hair composed of? • What 5 structures make up hair within skin? • What causes goose bumps? • What is sebum? Which gland secretes sebum? • Which gland aids in thermoregulation? How? • Which glad’s secretions combine with sebum to produce earwax? Why is this important? • What are the functions of nails? • What specifically are nails made of? • Of the 5 nail parts, name 3?

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