Chapter 6 Skin and the Integumentary System

1. Chapter 6Skin and the Integumentary System • Composed of several tissues • Protective covering • Retards water loss • Houses sensory receptors • Contains immune system cells • Synthesizes chemicals

2. Skin Cells • help produce ___________ needed for normal bone and tooth development • some cells (keratinocytes) produce substances that simulate development of some ______________

3. Layers of Skin • Epidermis • Subcutaneous layer • beneath _______ • not part of skin

4. Epidermis • lacks ____________ • keratinized • thickest on ______ and ___________ (0.8-1.4mm) • melanocytes provide ______________ • rests on basement membrane • stratified squamous

5. Production of new cells is balanced with the loss of _______ cells • Protects underlying tissues against _______ loss, mechanical injury, and the effects of harmful chemicals • Epidermal cells __________ and die as they are pushed to the surface

6. Epidermis Layers of Epidermis • stratum __________ (dead cells) • stratum lucidum • stratum granulosum • stratum spinosum • stratum ___________ (reproduce and grow)

8. Dermis • on average 1.0-2.0mm thick • contains dermal papillae • binds epidermis to _____________ • irregular _____ connective tissue • muscle cells • nerve cell processes • specialized sensory receptors • blood vessels • hair ___________ • glands

10. Subcutaneous Layer • hypodermis • loose _________ tissue • __________ tissue • insulates • major blood vessels

11. Hair Follicles • epidermal cells • tube-like depression • extends into dermis • _______ root • ________ shaft • _________ papilla • _______ epidermal cells • melanin • arrector pili muscle

12. A hair usually ________ for a while, rests, and then is replaced by a new hair. • Hair color is determined by _______ that direct the type and amount of pigment epidermal melanocytes produce • A bundle of smooth muscle cells forms the _________ ______ muscle and attaches to each hair follicle • One or more _________ glands are attached to each hair follicle

14. Nails • protective coverings • nail ______ • nail ______ • lunula • made of specialized _________ cells that keratinize

15. Sebaceous Glands • usually associated with hair __________ • holocrine glands • secrete _______ • Excess _________ causes acne • absent on palms and _______

16. Sweat Glands • sudoriferous glands • widespread in skin • originates in deeper dermis or hypodermis • _________ glands • _________ glands • ceruminous glands • mammary glands

17. Eccrine sweat glands • Most numerous • Found on the forehead, neck, back, palms, and soles • Respond to ___________ body temp or emotional stress • _________ and sebaceous gland activity decreases with advancing age • Sweat is mostly water with ________ and waste products

18. Apocrine Sweat Glands • Become ________ at puberty • Located in the _______ regions (armpit), groin, and around the nipples

19. Ceruminous glands are modified sweat glands that secrete __________ • Mammary glands are modified sweat glands that secrete _________

21. Regulation of Body Temperature • Regulation of body temperature is vital because heat affects the rates of metabolic reactions. Normal temperature of deeper body parts is close to a set point of ____°C (98.6°F). Skin plays a key role in body temperature homeostasis.

22. Heat production and loss • Heat is a by-product of ________ respiration. • The most active cells are ________ and heart muscle cells and the liver. • If body temperature rises above normal: -more blood enters ________ blood vessels (vasodilation).

23. If body temperature rises above normal: • _______ blood enters dermal blood vessels (vasodilation). • deeper blood vessels contract (vasoconstriction) diverting blood to the surface and the skin reddens

24. heat is lost to the outside by: • ____________ - rays move from warmer to cooler surroundings (primary way) • ____________ - heat moves from warmer objects to cooler objects it is touching • ____________ - heated air moving away from the body • ____________ - fluid evaporates from the surface carrying heat away (sweating)

25. If the body temperature drops below normal: • _________ blood vessels constrict, causing the skin to lose color • ________ glands become inactive • if heat is lost excessively, skeletal muscles involuntarily contract increasing cellular respiration and producing additional _____.

26. Problems in Temperature Regulation ________________ – abnormally high body temperature ________________– abnormally low body temperature

27. If the air is saturated with water, ______ may fail to evaporate, and body temperature may remain elevated (_____________) • Symptoms may begin with headache, dizziness, nausea, muscle cramping, and may lead to major organ failure • Lack of sweating – medical emergency

28. ________________ is lowered body temperature. • Symptoms begin with shivering, and leads to mental confusion, lethargy, loss of reflexes and ,consciousness, and eventually major organ failure

29. Skin Color • All humans have about the same number of melanocytes. Skin color differences are due to the amount of __________ produced

30. Genetic factors • _________ that control melanin production are inherited. • Dark skin is due to genes that cause large amounts of _________ to be produced • Lighter skin is due to genes that cause lesser amounts of ________ to form. • Mutant genes may cause a lack of melanin in the skin called _____________.

31. Environmental factors • Sunlight, ultraviolet light, and ___ rays darken existing melanin and stimulate _____ melanin production temporarily darkening the skin.

32. Physiologicalfactors • If blood is well oxygenated hemoglobin (blood pigment) is bright _____ causing the skin of light skinned people to appear pinkish. • If _______ content of blood is low hemoglobin is dark red and the skin appears _________ (cyanosis). • Dilated blood vessels can cause skin to redden

33. ____________ blood vessels cause a loss of reddish color. • ___________ in the subcutaneous layer may cause the skin to appear yellowish. • • Disease may affect skin color.

34. Healing of Wounds and Burns • Skin injuries trigger ____________. Blood vessels dilate forcing fluids to leave and enter the damaged tissue. The affected area becomes red, warm, swollen, and tender.

35. Cuts • A shallow cut in the epidermis is filled in by reproducing epithelial cells. • Deeper cuts into the dermis or subcutaneous layer cause a clot to form. • platelets become entrapped in _______ fibers (fibrin). • tissue fluids seep into the area • blood clot and dried fluids form a _______

36. ___________ begin to form new collagenous fibers that bind edges of the wound together • blood vessels extend beneath the scab • phagocytes remove ________ cells • a _______ where connective tissue replaces skin may appear

37. granulations (new blood vessel branch & fibroblasts) may form in large open wounds

38. Healing of Cuts

39. First degree burns (superficial partial-thickness burn) • only burns the ____________ • heals quickly with no scarring • the area is warm and red.

40. Second degree burns (deep partial-thickness burn) – • destroys some ________ and ________ • ________ appear • area becomes moist and firm and varies in color from dark red to waxy white

41. healing depends on the accessory organs that survive • skin usually recovers with no scar tissue unless an _________ occurs.

42. Third degree burns (full-thickness burns) • destroys the ________, ________, and the ____________ organs of the skin • injured skin may appear dry and leathery and varies in color from red to black to white • healing only occurs from epithelial cells growing inward from the margin of the burn

43. may require skin grafting: • ____________ - thin layer of skin from unburned area is removed and transplanted in injured area • ___________ - cadaveric skin is used to cover injury • skin substitutes - amniotic and artificial membranes human skin cultures - grow in lab and transplant • extensive scarring

44. Rule of Nines

45. Life Span Changes • Melanin production slows • _______ thins • Number of _____ follicles decrease • Nail growth becomes impaired • Sensory receptors decline • Body temperature unable to be controlled • Diminished ability to activate Vitamin ____ • Skin becomes scaly • Age spots appear • ________ thins • Dermis becomes reduced • Loss of ______ • Wrinkling • Sagging • ______________ glands secrete less oil

46. Clinical Application Acne Vulgaris • most common skin disorder • sebum and epithelial cells clog glands • produces whitheads and blackheads (comedones) • anaerobic bacteria trigger inflammation (pimple) • largely hormonally induced • androgens stimulate sebum production • treatments include antibiotics, topical creams, birth control pills