THE INTEGUMENTARY SYSTEM

1. THE INTEGUMENTARY SYSTEM

2. I. Introduction • Basics • Consists of skin, hair, nails, and cutaneous glands. • Largest organ of body • 15-20 sq. ft • 9 lbs • 0.5-4.00 mm thick

3. B. Layers • Epidermis • Epithelial t. • Dermis • Connective t. • Hypodermis (subcutaneous t.) • Loose connective t. (fat) • Not part of the skin • Anchors the skin to bone and muscle tissue

4. C. Functions • protection • Vitamin D production • Sensation • Thermoregulation • Excretion (small amount)

5. II. Epidermis • General • Keratinized, stratified, squamous epithelium • New epidermis every 35-45 days

6. II. Epidermis • General • Callus – gross thickening due to friction • Blister – acute trauma leads to separation of dermis and epidermis

7. Epidermis B. Cell types

8. II. Epidermis B. Cell types • Keratinocytes • Produce fibrous protein keratin • tough, water repellant protein • protects the skin and the underlying tissues from heat, microbes, abrasion and chemicals • Produced in deepest layer

9. Epidermis B. Cell types

10. B. Cell types 2. Melanocytes • Produce pigment melanin • Pigment is phagocytized by keratinocytes • Pigment granules protect keratinocytes from UV radiation

12. B. Cell types 3. Merkel’s cells • Associated w/nerve cell endings – touch reception • Scattered among Kerantinocytes 4. Langerhans’ cells • Macrophage-like • Defend against microorganisms

15. Epidermis • C. Layers

16. Hint to remember the layers: Can Little Girls Speak German • Can Corneum • Little Lucidum • GiRls GRanulosum • SPeak SPinosum • GERMan GERMinativum

18. II. Epidermis C. Layers • Stratum Basalis • Also known as Stratum Germinativum • Single layer • Mitotic

19. Receive nutrients by diffusion from dermis • Composed of columnar keratinocytes • melanocytes • Merkel’s cells C. Layers • Stratum Basalis

20. C. Layers • Called the “Spiny Layer” • Less mitotic • Cells are many sided keratinocytes • often called “Prickle Cells” 2.Stratum Spinosum

21. C. Layers 2.Stratum Spinosum • Scattered among keratinocytes are Langerhans’ cells

22. Note: The Stratum Basalis and Stratum Spinosum • contain the only epidermal cells that receive adequate nourishment • As the daughter cells are pushed upward, away from the source of nutrition, they gradually die and their soft protoplasm becomes keratinized (hard).

23. C. Layers • Stratum Granulosum • Granular layer • Keratinization begins • Cells die • Thin layer 2-3 cell layers

24. C. Layers 4. Stratum Lucidum • Clear layer • Found in thick skin only as palms and soles of feet • Contain Keratin fibrils • Cells begin to degenerate

25. C. Layers 5. Stratum Corneum • Horny Layer • 20-30 cell layers • ¾ of thickness

26. C. Layers • Stratum Corneum • Consists of dead flat keratinized cells being sloughed off

27. II. Epidermis

28. III. Dermis

29. III. Dermis • General • Strong, flexible, connective tissue • Thickness: 0.6 – 3 mm

30. III. Dermis • General • Has collagenous & reticular fibers

31. A. General 4. Contains • Blood vessels • Nerves • Hair follicles • Sebaceous glands • Sweat glands • Nail roots

32. A. General 5. Epidermis projects into dermis to form • Sebaceous glands • Sweat glands • Hair follicles

34. III. Dermis B. Layers

35. B. Layers • Papillary Layer • Closest to epiderms • Made of areolar, loose con. t. • Has Dermal Papillae • Finger-like projects that indent into the epidermis

36. c. Has Dermal Papillae • Contain • Capillaries • pain receptors • Meisner corpuscles: light touch receptors • Finger prints

37. III. Dermis B. Layers 2.Reticular layer • Deepest layer • Comprises 4/5 of dermis • Made of dense irregular connective tissue

38. III. Dermis B. Layers 2.Reticular layer • Rich in blood vessels and nerve • Pacinian corpuscles – sense deep pressure, heat and cold

39. III. Dermis B. Layers 2.Reticular layer • f. Tension lines or cleavage – separation of collagen bundles • g. Flexure line – folding of dermis at joints of wrists, palms, fingers toes

40. IV. Hypodermis • Areolar and adipose tissue • Anchors skin to organs • Insulates, absorbs shock, stores fat

41. V. Skin Appendages • General • Organs that develop from the embryonic epidermis • Also called epidermal derivatives

42. V. Skin Appendages • General • Includes • Hair • Sweat glands • Sebaceous glands • Finger nails • Tooth enamel

43. V. Skin Appendages B. Hair • Is fused keratinized cells • Protects against • Scalp injury • Sun • Heat loss

44. B. Hair 3. Structure • Shaft • Above surface • Shape determines curliness • Round = straight • Oval = wavy • Flat = kinky

45. 3. Structure a. Shaft • Root • Extends from epidermis to dermis • Extends into hypodermis in scalp

46. Note: The root and shaft are made of 3 tubes

47. Note: 3 tubes • cuticle: outer tube 1 layer of heavily keratinized cells. • cortex: middle tube several layers of cells w/ pigments in dark hair and air bubbles in white hair. • medulla: inner tube made of 2 -3 rows of cells with pigments and air spaces.

48. B. Hair 4. Follicle • Provides nutrients • Matrix produces hair • Arrector pili muscle – goose bumps

49. V. Skin Appendages • Hair 4. Split ends – cuticle wears away • Color results from melanin (black, brown, yellow) • Hair growth – nutrition, hormones

50. V. Skin Appendages • Hair • Kinds of hair • Vellus hair: fine pale body hair of women and children • Terminal hair: coarse, scalp, pubic region, male body hair P141 hirsutism