1. Integumentary System

2. 17. Integumentary System - covering of the body
A. Includes - skin, hair, and nails

3. Skin
18. Body’s largest organ

4. B. Functions – most important is protection

5. Functions
a. Holds fluids in

6. Functions
b. Keeps disease causing microorganisms out

7. Functions
c. Pigments protect from UV rays

8. Functions
d. Makes vitamin D from sunlight and cholesterol

9. Functions
e. Nerve endings in skin sense heat, cold, and pressure

10. Made of two main layers

11. 19. Epidermis - outer layer, stratified squamous

12. A. Stratum Corneum - outer layer of dead cells, contain keratin

13. Keratin a. A tough fibrous protein, waterproofs
forms basic structure of hair, nails, and cuticles
soft keratin
hard keratin

14. In animals, keratin also makes:
cow horns, reptile scales, bird feathers, and porcupine quills

15. Replaced
b. Once every days

16. B. Stratum Germinativum – bottom layer of epidermis-mitosis happens

17. Melanocytes
a. contain melanin pigment, protection from UV

18. Light and dark skin
b. We all have roughly the same amount of melanocytes, the difference is in the amount of melanin produced

19. Freckles and moles
Concentrated areas of melanin

20. Importance of melanin
c. absorbs Ultraviolet Radiation from the sun

21. 20. Dermis – thick, inner layer of the skin, contains living cells

22. Nerve endings
A. Feel our environment

23. Blood vessels
B. Bring nutrients to cells and help regulate body temperature

24. Hot – vessels widen and release heat through the skin
Cold – vessels narrow to keep heat in the body

25. Glands
C. Sacs that release contents at the surface of the skin

26. Sweat glands
a. Produce and secrete sweat – water, salts, and cellular wastes

27. Purpose
Helps cool the body as sweat evaporates

28. Smell?
Sweat itself doesn’t smell, it is the bacteria that feed on the sweat

29. Sebaceous glands
b. Produce an oil called sebum

30. Purpose
lubricate the skin and hair, kills many bacteria

31. Acne – inflammation of the sebaceous glands

32. Whitehead – glands are blocked with sebum
Blackhead – sebum dries and darkens
Pimple – glands become infected with bacteria

33. Hair follicle
D. Sac that surrounds the hair and it’s root

34. Arrector pili
E. Smooth muscle cells that pull the hair upright when cold or scared

35. 21. Hypodermis
- Layer of fat and connective tissue below the dermis

37. Issues with skin

38. Blister
A. Friction causes the epidermis to separate from the dermis, fluids fill the space

39. Callus
B. Increased pressure causes the epidermis to thicken

40. Burns
C. Tissue damage caused by heat, cold, chemicals, electricity, radiation

41. 1st degree
a. Only the epidermis is damaged, redness, swelling, pain

42. 2nd degree
b. Damage epidermis and upper part of dermis, blisters form

43. 3rd degree
c. Damage entire thickness of skin, appears gray-white, cherry red, or black, no pain

44. Melanoma
D. Cancer of the melanocytes, most dangerous of skin cancers

45. Warning signs A – asymmetry B – border irregularity C – color
D – diameter

46. As it evolves…
Old moles can evolve into cancerous ones

47. 23. Hair – made of dead, keratinized cells
Hard keratin:
More durable
Cells don’t flake off

48. A. Functions – not really for warmth
a. Sense insects on skin before they bite or sting b. Eyelashes shield the eyes c. Nose hairs filter particles before we inhale

49. Hair structure
a. Shaft – projects from the skin b. Root - below the skin, living cells dividing c. Hair follicle – tube like pockets that extend into the dermis and house the hair roots

50. Shaft layers
a. Medulla – central core of large cells and air spaces

51. Shaft layers
b. Cortex – several layers of flattened cells surrounding the medulla

52. Shaft layers
c. Cuticle – outermost layer of cells that overlap like shingles – provides strength and keeps inner layers tightly packed
Subjected to the most abrasion, it tends to wear away at the ends of the shaft which allows the inner layers to separate causing split ends

53. Split ends

54. Follicle shape – determines hair texture
a. Straight hair – round follicles
b. Curly hair – flat follicles

55. Hair growth
E. Most grow for several years and then fall out

56. 24. Nails – solid plates of dead, keratinized epidermal cells

57. Functions
a. Protect tips of fingers and toes b. “tool” for digging, scratching, picking up small things

58. Nail structure
a. Nail plate – body of the nail, hard

59. Nail structure
b. Nail bed – lies under the nail plate, gives nails their pink color

60. Nail structure
c. Nail matrix – where nail cells are produced, if damaged, nail will not grow

61. Nail structure
d. Cuticle – flap of skin that covers the nail root

62. Nail structure
e. Lunula – white crescent shape at base of nail, visible part of the matrix
Thicker cells of the matrix make it look white – damage to this will permanently deform the nail
Even if the nail is removed the lunula will remain and look like a small nail imbedded in the finger

63. Nail growth C. Grow continuously without shedding, avg. 3 mm a month
Fingernails require 3 to 6 months to regrow completely, and toenails require 12 to 18 months

64. 2 feet, 11 inch thumb nail
Lee Redmond, right, former record holder for longest fingernails with Melvin Booth, the male owner of the longest finger nails.