1. The Integumentary System

3. Integumentary System Blood vessels and nerves are found in the dermis Deep to the dermis, is the subcutaneous layer (hypodermis)

4. Integumentary System Functions of skin and subcutaneous layer: ◦ Protection ◦ Excretion ◦ Maintenance of body temperature ◦ Synthesis if vitamin D ◦ Storage of fats ◦ Detection of touch, pressure, pain, temperature

5. THE EPIDERMIS Integumentary System

6. The Epidermis Stratified squamous epithelial tissue ◦ Mostly keratinocytes (contains keratin) Is comprised of several layers (deep to superficial) Thin Skin – covers most of your body Thick skin – palms of hands, soles of feet

7. THE DERMIS Integumentary System

8. The Dermis Lies between the epidermis and the subcutaneous layer

9. Dermal Strength and Elasticity Dermis contains both collagen and elastic fiber ◦ Allows dermis to tolerate limited stretching Water also helps with flexibility and resilience ◦ Pinch test for dehydration Aging, hormones, UV radiation damages elastic fibers ◦ Leads to wrinkles and sagging skin

10. Dermal Strength and Elasticity Extensive stretching of dermis can exceed the elastic capabilities of the skin ◦ Complete recoiling of fibers is prevented ◦ Result is stretch marks Retin-A (derivitave of Vitamin A) can help repair the dermis and can lessen appearance of wrinkles and stretch marks.

11. THE SUBCUTANEOUS LAYER Integumentary System

12. The Subcutaneous Layer Also known as the hypodermis Consists of areolar and adipose tissue ◦ Very elastic Superficial region contains blood vessels Subcutaneous fat serves as an insulator and a major energy reserve for the body.

13. The Subcutaneous Layer At puberty, distribution of fat starts to differ between the sexes ◦ Men tend to store fat at the neck, arms, low back, and buttocks ◦ Women tend to store fat at the breasts, buttocks, hips and thighs ◦ Both can accumulate fat in the abdominal region

14. ACCESSORY STRUCTURES Integumentary System

15. Hair and Hair Follicles Hair – cover almost every surface of your skin ◦ Exceptions are sides and soles of feet, palms of hands, sides of toes and fingers, lips, portions of external genitalia Body has 2.5 million hairs  75% NOT on your head Hair is a nonliving structure produced by hair follicles ◦ Made of the protein keratin

16. Hair and Hair Follicles Function of hair on head ◦ Protect from UV radiation ◦ Cushion light blows to head ◦ Insulate skull In nostrils and ear: ◦ Prevent entry of foreign particles All hair serve as sensory receptors

17. Hair and Hair Follicles Hair coloration is from the melanocytes producing varying amounts of melanin in the hair follicle Different forms of melanin will give hair a dark brown, yellow-brown, or red appearance

18. Glands In the Skin Sebaceous (Oil) Glands Can secrete oil from hair follicle or directly onto skin The secreted material is called sebum ◦ Made of fatty acids, cholesterol, proteins, and electrolytes ◦ Inhibits bacteria growth, lubricates and protects hair, and conditions surrounding skin

19. Glands In the Skin Sweat Glands ◦ Also known as sudoriferous glands ◦ Two types  Apocrine sweat glands  Found in armpits, around nipples, and pubic region  Secrete sweat into hair follicles  Sticky, cloudy, odorous secretion  Begin secreting at puberty  This sweat is a nutrition source for bacteria, which intensifies odor

20. Glands In the Skin Sweat Glands (Con’t) ◦ Two types  Merocrine sweat glands  Discharge secretion directly onto surface of skin  More numerous (2-5 million) than apocrine glands  Palms and soles have highest number  3000 per square inch  Secretion is 99% water with some electrolytes (mainly sodium chloride)

21. Glands In the Skin Sweat Glands (Con’t) ◦ Two types  Merocrine sweat glands  Functions:  Cool surface of skin (maintain homeostasis)  Excrete water and electrolytes  Provide protection  Dilute harmful chemicals  Discourages growth of mmicroorganisms

22. Nails Protect exposed dorsal surfaces of the tips of the fingers and toes Major Parts: ◦ Nail body – visible portion of nail ◦ Nail bed – lies under nail body ◦ Free edge – distal portion extending past nail bed ◦ Nail root – forms the nail ◦ Eponychium (cuticle) – skin flap covering proximal nail body ◦ Lunula – pale crescent at proximal end of nail body

24. INJURY RESPONSE Integumentary System

25. Injury Response Excellent regeneration capabilities and response to stresses. Calluses form when repeated stresses from manual labor are placed on the skin ◦ The stem cells of stratum germinativum divide more rapidly, thickening the skin in that area

26. Injury Response The process of injury repair can be slow Infection and fluid loss can complicate repair The type of injury also determines rate of repair ◦ Thin, straight cut (incision) will generally heal more quickly than a scrape (abrasion) because of the relative surfaces involved

27. Injury Response Bleeding occurs only when the damage extends into the dermis. Why? ◦ No vessels in epidermis

28. Injury Response Steps to injury response Step 1 Bleeding occurs and mast cells trigger the inflammatory response

29. Injury Response Step 2 Blood clot (scab) forms  Restores integrity of epidermis  Restricts microorganisms from entering area Macrophages patrol area collecting debris and pathogens

31. Injury Response Step 3 Over time, deeper portion of clot dissolves Number of capillaries decline Fibroblast activity leads to increase in collagen fibers and ground substance Epidermal cells have migrated over the network of collagen fibers

32. Injury Response Step 4 After several weeks, the scab is shed The repairs do not restore the integument to its original condition ◦ Dermis will contain abnormally large numbers of collagen fibers, and few capillaries Severely damaged hair follicles, glands, muscle and nerve cells are seldom repaired ◦ Replaced by fibrous tissue (Scar)

34. AGING Integumentary System

35. Aging and the Integument Effects of aging on the integument ◦ Thinning epidermis

36. Aging and the Integument Effects of aging on the integument ◦ Decreased vitamin D production  Muscle and bone weakness

37. Aging and the Integument Effects of aging on the integument ◦ Decreased melanocyte activity  More sensitive to sun

38. Aging and the Integument ◦ Decline in glandular activity  Dry, scaly skin. Less perspiration means increased overheating

39. Aging and the Integument Effects of aging on the integument ◦ Reduced blood supply to dermis ◦ Hair follicles stop functioning  Thinner, finer hair

40. Aging and the Integument Effects of aging on the integument ◦ Dermis thins  Sagging and wrinkling occur

41. Aging and the Integument Effects of aging on the integument ◦ Decrease in sex hormones  Hair characteristics and fat distribution change  People of both sexes age 90-100 tend to look alike

42. Aging and the Integument Effects of aging on the integument ◦ Skin repairs more slowly  Repairs can take twice as long as a young adult  Recurring infections may result

43. Skin Homeostatic Imbalances Infections ◦ Athletes foot  Caused by fungal infection ◦ Boils and carbuncles  Caused by bacterial infection ◦ Cold sores  Caused by virus

44. Skin Homeostatic Imbalances Infections and allergies ◦ Contact dermatitis  Exposures cause allergic reaction ◦ Impetigo  Caused by bacterial infection ◦ Psoriasis  Cause is unknown  Triggered by trauma, infection, stress

45. Skin Homeostatic Imbalances Burns ◦ Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals ◦ Associated dangers  Dehydration  Electrolyte imbalance  Circulatory shock

46. Rule of Nines Way to determine the extent of burns Body is divided into 11 areas for quick estimation ◦ Each area represents about 9% Figure 4.11a

47. Severity of Burns First-degree burns ◦ Only epidermis is damaged ◦ Skin is red and swollen Second degree burns ◦ Epidermis and upper dermis are damaged ◦ Skin is red with blisters Third-degree burns ◦ Destroys entire skin layer ◦ Burn is gray-white or black

48. Critical Burns Burns are considered critical if: ◦ Over 25% of body has second degree burns ◦ Over 10% of the body has third degree burns ◦ There are third degree burns of the face, hands, or feet

49. Skin Cancer Cancer – abnormal cell mass Two types ◦ Benign  Does not spread (encapsulated) ◦ Malignant  Metastasized (moves) to other parts of the body Skin cancer is the most common type of cancer

50. ABCD Rule A = Asymmetry ◦ Two sides of pigmented mole do not match B = Border irregularity ◦ Borders of mole are not smooth C = Color ◦ Different colors in pigmented area D = Diameter ◦ Spot is larger then 6 mm in diameter