1. Integumentary System

2. Sites used http://www. meddean. luc

3. Skin ~9 lbs. (4.1 kgs) Covers S.A. of 15-20 ft2 (1.4 to 1.9 m2)
Every square inch contains 15’ blood vessels, 12’ nerves, 650 sweat glands, 100 oil glands, 1500 sensory receptors, & 3 million cells
Thickness varies from 1/32” to 1/8”
Skin cells die & replaced continuously
3 layers = epidermis, dermis & hypodermis

4. Skin-Major Functions Protects Excretion/Secretion
Helps regulate body temperature
Sensation (Cutaneous sensation)
Promotes vitamin D synthesis
Acts as reservoir for blood

5. Protects
3 ways
Chemically
Physically
Biologically

6. Protects-Chemically
Acidic skin secretions inhibit bacteria from multiplying
Substances in sebum (oil) kill some bacteria
Melanin-shield skin from UV rays

7. Protects-Physically Keratinized cells-ex.epidermis, hair and nails
Barrier to invading organisms

8. Protects-Biologically
Dermal macrophages-2ndline of defense against bacteria
Epidermis contains macrophage like Langerhan’s cells = immunity

9. Excrete/Secrete Sweat-nitrogenous waste, sodium chloride
Sebum-secreted by sebaceous glands

10. Regulate Body Temp. Evaporation of sweat
Dermal blood vessels dilate and constrict

11. Cutaneous Sensation
Sensory receptors-Meissner’s, Pacinian, Ruffini’s, Krauses, free nerve endings

12. Vitamin D Synthesis.
Exposed to UV-skin converts cholesteral molecules to Vitamin D

13. Reservoir for blood
Shunted from skin to general circulation ex. To working muscles

14. Skin
3 layers
Epidermis
Dermis
Hypodermis

15. 1. Epidermis Most superficial layer of skin
First barrier of protection
Principle (main) cell type in epidermis = keratinocytes
4-5 layers
4 types of epidermal cells

16. 2. Dermis Contains sebaceous and sweat glands Sensors:
2-A) Pacinian corpuscle – heavy touch & vibratiions
2-B) Meissner’s corpuscle – light touch

17. 3. Hypodermis Most of the blood flow (arteries & veins)
Contains fat for insulation & cushioning

18. 4. Hairs
Protection
Decrease heat loss
Errector pilius – pulls hair errect during stress

19. Common Disorders: Eczema Psoriasis Freckles/Moles
Athelete’s Foot/Jock Itch
Melanoma
Calluses/Corns
Bruising
Impetigo

28. Epidermal Cells
Keratinocytes: compose most of epidermis; make protein keratin
Keratin: waterproofs and protects skin
Melanocytes:synthesize melanin
Melanin protects against UV damage
Merkel cells: associated with sensory receptors (touch)
Langerhan’s cells: macrophages used in defense against microorganisms

29. Skin thick, All layers

31. Stratified Squamous Epithelium

32. Epidermis Layers

33. Stratum Germinativum

34. Stratum Spinosum

35. Close Up of Stratum Spinosum

36. Stratum Spinosum

37. Stratum Granulosum

38. Stratum Lucidum

39. Stratum Corneum

40. Skin thick, All Epidermis Layers

41. Skin Thin All epidermis layers

42. Dermis

43. Skin thin Dermis all layers

44. Skin Thick Dermis All Layers

45. Papillary Dermis

46. Reticular Dermis

47. Skin Appendages

48. Hairy Skin with intact and disintegrating sebum containing secretory cells

49. Hairy Skin with Sebaceous Gland

50. Skin with hair follicles

51. Hair Follicle

52. Hair Follicle with labels

53. Thick Skin with excretory duct and secretory tubulus

54. Thick skin with merocrine sweat gland