The Integtumentary System

1. The Integtumentary System

2. Functions of the Integument • Protection • Excretion • Sensory • Water balance • Thermoregulation • Endocrine (Vitamin D)

3. Some facts about skin • Largest organ of the Body • Approximately 2 square meters or 22 square feet • About 5 kg (11 pounds) • Ranges in thickness between 0.5 mm (genitals, lips, eyelids) to 5 or 6 mm on the soles of the feet. • Three layers, from superficial to deep: • Epidermis - outer layer of dead, keratinized cells • Dermis - dense irreg. c.t., nerves, vessels, etc. • Hypodermis - mostly subcutaneous adipose tissue

4. Slice o’ skin

5. Skin: Thick Stratum granulosum Stratum corneum Stratum spinosum Stratum Basale Dermis

6. Thin skin: scalp Human scalp

7. Scalp: deep Human scalp

8. Organization of the Epidermis Figure 5–2

9. The Epidermis

11. Melanocytes Figure 5–5

12. Skin Glands • There are two general types of skin glands: • Sudoriferous glands (sweat glands). • Eccrine glands - produce watery sweat for cooling, waste metabolite excretion & electrolyte excretion. Found all over the body except nail beds, genitals, & ear drums. Most dense on palms, soles, forehead & chest. • Apocrine glands - produce “stinky” sweat. Secrete a thicker, protein and lipid rich fluid and “pheromones”. Concentrated in arm pits, pubic region, areolae. Activated by the stress response or sexual arousal (sympathetic n.s.)

13. Skin Glands b. • Mammary glands - Mammary glands are specialized sudoriferous glands. They produce milk. And yes, men have them too! • Ceruminous glands - Modified sweat glands that line the external auditory canal. They make “cerumen”, also known as ear wax. 2. Sebaceous glands - produce oily secretion called “sebum”. These glands open onto the hair follicles and the oil keeps hair supple and skin water resistant..

14. The Dermis: Glands

15. Sebaceous Glands Figure 5–10

16. Apocrine Sweat Gland Figure 5–11a

17. Merocrine Sweat Gland

18. Other Integumentary Glands • Mammary glands: • produce milk • Ceruminous glands: • protect the eardrum • produce cerumen (earwax)

19. Control of Glands • Autonomic nervous system: • controls sebaceous and apocrine sweat glands • works simultaneously over entire body • Merocrine sweat glands: • are controlled independently • sweating occurs locally

20. Epidermal Appendages: Hair

21. Structure of a Hair Figure 5–9d

22. Connective tissue Root sheath Follicle wall Hair follicle: cross section Internal root sheath Cuticle Cortex Medulla Hair follicle in cross section

23. Structures of a Follicle Figure 5–9c

24. Epidermal Appendages: Nails

25. Ridges and Ducts Figure 5–4

26. Repair of Localized Injuries to the Skin: Step 1 • Bleeding occurs • Mast cells trigger inflammatory response

27. Repair of Localized Injuries to the Skin: Step 2 • A scab stabilizes and protects the area

28. The Inflammatory Response • Germinative cells migrate around the wound • Macrophages clean the area • Fibroblasts and endothelial cells move in, producing granulation tissue

29. Repair of Localized Injuries to the Skin: Step 3 • Fibroblasts produce scar tissue • Inflammation decreases, clot disintegrates

30. Repair of Localized Injuries to the Skin: Step 4 • Fibroblasts strengthen scar tissue • A raised keloid forms

31. Stages of wound healing • Inflammatory • Migratory • Granulation • Maturation • Fibrosis: scar tissue formation • Hypertrophic scar is one that remains within the boundaries of the original wound. • Keloid scar is one that extends to surrounding tissue beyond the original wound.

32. Burns

33. Rule of Nines • To estimate burn damage, surface area is divided into multiples of 9 Figure 5–14

34. First degree (partial thickness)

35. Second Degree

36. First & second degree burns

37. Third degree (full thickness)

38. Third degree burns

39. Skin Cancer • Basal cell carcinoma - 75%, arise from epidermal cells. Rarely metastasize to other tissues. Easily removed. • Squamous cell carcinoma - around 20%, may or may not metastasize. Also from epidermal tissue. • Malignant melanoma - remaining 5%, arise from melanocytes. Often delayed reaction to sun exposure by 10 - 20 years. Poor prognosis, they metastasize very rapidly once they begin to grow.

40. ABCDs of skin cancer detection

41. Risk factors for skin cancer • Skin type - lighter skin pigmentation = higher risk • Sun exposure - lower latitude, more direct sun. Longer time, greater exposure. • Family history - Genetics nearly always plays at least some role in susceptibility to disease. • Age - older = longer exposure. • Immune system health - people with compromised immune systems are at greater risk.

42. Skin Cancer Figure 5–6

43. Fungating Melanoma

44. Other skin pathologies • Athlete’s foot - caused by a fungus • Cold sore - herpes simplex virus type I. HSV II causes genital herpes. • Acne - inflamed sebaceous glands. Can be seriously disfiguring. Accutane™ and Retin-A™ are prescription treatments which are derived from vitamin A and have proven helpful in severe cases. OTC treatments include salicylic acid and benzoyl peroxide with variable efficacy. • Impetigo - superficial infection caused by staphylcocci or streptococci, two genera of bacteria very common to skin. • Warts - raised lesions caused by papilloma virus. HPV causes genital warts, a sexually transmitted infection, that is often associated with cervical cancer in women.

45. Effects of Aging • Epidermal thinning • Decreased numbers of Langerhans cells • Decreased vitamin D3 production • Decreased melanocyte activity • Decreased glandular activity (sweat and oil glands)

46. Effects of Aging • Reduced blood supply • Decreased function of hair follicles • Reduction of elastic fibers • Decreased hormone levels • Slower repair rate

47. Another great use for skin