Integumentary System

1. Integumentary System • _______________ membrane (skin) – our largest organ • Accounts for _____ of body weight • Divided into two distinct layers • __________ • __________ • Accessory structures • Subcutaneous layer (_______________)

2. Functions Of The Integument • _____________ and insulates deeper organs • _____________ body from abrasion, trauma, chemicals, pathogens, temperature extremes and UV rays • ___________ and ___________ • Contains ____________________associated with nerve endings • Synthesis and storage of nutrients (______________)

3. Integumentary Structures • Components of the Integumentary System Figure 5-1

4. Skin Structures

5. The Epidermis- Four Main Cell Types • _____________ - found in basal layer, manufacture and secrete pigment • ______________ - basal layer, attached to sensory nerve endings • _______________ – Arise from deepest layer of epidermis to stratum spinosum • Produce __________ – a tough fibrous protein • Produce _____________ and __________ • Keratinocytes are dead at skin's surface • __________________ - stratum spinosum, part of immune system macrophage-like

6. The Epidermis • Stratified squamous epithelium • Several distinct cell layers • ________________—five layers on palms and soles • ________________—four layers on rest of body

7. Layers of The Epidermis • Stratum ____________ • Most _______________ layer • Dead, flattened (squamous) cells • Abundant keratin - __________ (cornified) tough, water-resistant protein • Protects skin against abrasion and penetration • Stratum ___________ (clear layer) • Occurs only in thick skin – palms and soles • Composed of a few rows of flat, dead keratinocytes

8. Layers of The Epidermis • Stratum ___________ (grainy layer) • Consists of keratinocytes • Tonofilaments • Keratohyaline granules – help form keratin • Lamellated granules – contain a waterproofing glycolipid • Stratum ___________ (spiny layer) • “Spiny” appearance caused by artifacts of histological preparation • Contains thick bundles of intermediate filaments (tonofilaments) • Resist ____________ • Contain protein _____________ • Contains _____________ Langerhans cells

9. Layers of the Epidermis • Stratum ___________ • __________ layer of epidermis • Attached to underlying dermis • _____________ actively divide • __________– associated with sensory nerve ending • __________ – secrete the pigment melanin

10. Epidermal Cells and Layers of the Epidermis Figure 5.3

11. Sources of Skin Color • Melanocytes • Make ________from tyrosine • Melanin provides _____ protection • Gives ____________ to brown-black color • Carotene • Contributes _________________ • Provided from _____ (carrots and tomatoes) • Hemoglobin - blood pigment • Caucasian skin contains little ___________ • Allows __________ color of blood to show through

12. Dermis • _____________ major layer of the skin • Provides mechanical strength, ___________, and protection for underlying tissues • ___________________and contains a variety of sensory receptors that provide information about the external environment • Two layers • ________________– includes dermal papillae • ______________- deeper layer – 80% of thickness of dermis • _________________- creases on palms

13. Layers of the Dermis • Papillary layer • Underlies epidermis • Named for dermal papillae • Aerolar __________________ • Supports, nourishes epidermis • Provides sensory nerves, lymphatics, and ____________ • Reticular layer • Tough, dense, fibrous layer • Dense __________________ • Collagen fibers - limit ________ • Elastic fibers - provide __________ • Blends into papillary layer (above) • Blends into _______________ layer (below)

14. Dermal Components • Epidermal accessory organs • Cells of connective ________________ • Communication with other organ systems • _______________ • ______________ • _____________ • Sensation • Control of blood flow and secretion

15. Subcutaneous Layer - Hypodermis • Composed ____________________________________________ • ______________ skin position • Loosely attached to dermis • Loosely attached to muscle • Contains _________________cells • Provides ________________ • ______________ underlying organs • Safely receives hypodermic needles

16. Hair • ___________ strands of dead keratinized cells produced by hair follicles • Contains hard ___________ which is tougher and more durable than soft keratin of the skin • Chief parts of a hair • ___________ – imbedded in the skin • ____________ – projects above skin's surface

17. Hair • Hair Shaft organized into three concentric layers • ___________ – central core • __________ – surrounds medulla • ___________ – outermost layer • Pigmented by melanocytes at the base of the hair

18. Cross Section of a Hair Figure 5.7a, b

19. Hair Follicle • ____________extending from the epidermal surface into the dermis • Deep end is expanded forming _____________ • __________ - nipple-shaped indentation with blood vessels and nerves    • _________ - germinal layer of cells (actively dividing cells) right above the papilla • A knot of _____________ (a root hair plexus) wraps around each hair bulb • _______________stimulates these endings, hence our hairs act as sensitive touch receptors • ____________muscle - bundle of smooth muscle contracts to make hair stand erect

20. Longitudinal Section of Follicle Figure 5.7c, d

21. Hair Follicles

22. Hair Function and Distribution • Functions of hair include: • Helping to maintain _____________ • Alerting the body _________________on the skin • Guarding the scalp against ____________, heat loss, and sunlight • Hair is distributed over the entire skin surface except • __________,__________,________ • Nipples and portions of the external genitalia

23. Sebaceous Glands (oil glands) • Occur over entire body - Except palms and soles • Simple ____________________ • _______________ secretion – entire cell breaks up to form secretion • Secretes an oily substance called _________ • Most are associated with a _____________ • Functions of sebum • Softens and lubricates hair and skin • ___________________ • ___________________

24. Sweat (Sudoriferous) Glands • Two types: • __________________ • Most abundant sweat gland • “True sweat” • 99% water with some salts • Contains traces of metabolic wastes ~ 2% urea • Role in _________________ • Widely present in skin (up to 500/cm2) • ______________ • Odorous secretion • Absent before ___________ • Present in axillary, areolar, anal and genital areas

25. Eccrine (Merocrine) Gland Figure 5.10b

26. Nails • _____________ modification of epidermis made of hard keratin • Parts of the nail • Free edge • Body - dense mass of _______________ • Root • Nail folds • _____________– cuticle

27. Skin Injury and Repair • Four Stages in Skin Healing • ______________ • Blood flow increases • Phagocytes attracted • ______________ • Cell division and migration • ___________ formation

28. Bleeding occurs at the site of injury immediately after the injury, and mast cells in the region trigger an inflammatory response. After several hours, a scab has formed and cells of the stratum germinativum are migrating along the edges of the wound. Phagocytic cells are removing debris, and more of these cells are arriving with the enhanced circulation in the area. Clotting around the edges of the affected area partially isolates the region. Epidermis Scab Migratory epithelial cells Macrophages and fibroblasts Dermis Sweat gland Granulation tissue Skin Injury and Repair

29. After several weeks, the scab has been shed, and the epidermis is complete. A shallow depression marks the injury site, but fibroblasts in the dermis continue to create scar tissue that will gradually elevate the overlying epidermis. One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblast activity. Phagocytic activity around the site has almost ended, and the fibrin clot is disintegrating. Scar tissue Fibroblasts Skin Injury and Repair

30. Skin Injury and Repair Table 5-1

31. Aging of the Skin • Major Age-Related Changes • _____ and infection increase • Immune cells ___________ • Sun protection diminishes • Skin becomes dry, ________ • Hair thins, ________ • Sagging, _________ occur • Heat loss ___________ • Repair ________

32. Effects of UV Radiation • Beneficial effect - activates synthesis of vitamin D3 • Harmful effects • ___________ • Wrinkles, ___________ • ___________________ • ___________________

33. Types and Growth of Hair • _________ hairs • Body hairs of women and children • _________ hairs • Hair of scalp • Axillary and pubic area (at puberty) • _______________________ • Due to aging • Male pattern baldness

34. Burns • Classified by severity • _______________– only upper epidermis is damaged • _______________– upper part of dermis is also damaged • _____________ appear • Skin heals with little scarring • ___________________ • Consume ______________ of skin • Burned area appears white, red, or _______________

35. Estimating Burns Using the Rule of Nines Figure 5.11a

36. Skin Cancer • _______________________ • Least malignant and ________________ • _______________________ • Arises from ________________ of stratum spinosum • ________________ • A cancer of _________________ • The most dangerous type of skin cancer

37. Skin Cancer Squamous cell carcinoma Squamous cell carcinoma Basal cellcarcinoma Melanoma Figure 5.12

38. The Skin Throughout Life • ______________ • Develops from embryonic ectoderm • ________________ • Develop from mesoderm • _________________ • Develop from neural crest cells

39. The Skin Throughout Life • Fetal skin • Well formed after the ________________ • At 5-6 months • The fetus is covered with __________ (downy hairs) • Fetal sebaceous glands produce ___________________

40. The Skin Throughout Life • Middle to old age • Skin thins and becomes _____________ • Shows ____________ effects of environmental damage • Skin ______________ become more common