1. Functions, Homeostatic Imbalances, Burns, Cancer, Development
Chapter 5 c
Functions, Homeostatic Imbalances, Burns, Cancer, Development

2. Functions of the Integumentary System
Protection
Body Temperature Regulation
Cutaneous Sensation
Metabolic Functions
Blood Reservoir
Excretion

3. Protection The skin has three types of barriers: Chemical
Physical/Mechanical
Biological

4. Protection Chemical Barriers
Melanin - pigment that forms a shield to prevent UV damage
Skin secretions – low (acidic) pH secretions in sweat called Acid Mantle inhibits bacterial growth
Skin secretions – sebaceous glands secrete sebum with substances that kill bacteria

5. Protection Mechanical Barriers Keratinized cells – hardness
Continuity of skin
Glycolipids waterproof – block diffusion of water and water soluble substances
Preventing their loss from and entry into the body

6. Substances that do penetrate:
Lipid soluble substances like oxygen, carbon dioxide, vitamins A, D, E, & K, and steroids
Oleoresins of certain plants like poison ivy and poison oak

7. Substances that do penetrate:
Organic solvents such as acetone, drycleaning fluid, and paint thinner (which dissolves the cell lipids)
Salts of heavy metals such as lead, mercury, and nickel

8. Homeostatic imbalance
Organic solvents and heavy metals can be lethal
Passage of organic solvents through the skin into blood can cause the kidneys to shut down or cause brain damage
Absorption of lead results in anemia and neurological defects

9. Never Handle Organic solvents or heavy metals with your bare hands

10. Protection Biological Barriers Langerhans’ cells of the epidermis
Active elements of the immune system. They present antigens (foreign substances) to specialized white blood cells

11. Protection Biological Barriers Macrophages in the dermis
If bacteria or viruses get past the Langerhan’s cells in the epidermis, the dermal macrophages will get rid of them

12. Protection Biological Barriers DNA
Usually shielded by melanin but electrons in DNA can absorb UV rays and transfer as heat to water molecules

13. Body Temperature Regulation
Our bodies must maintain its temperature within homeostatic limits.
As long as the external air temperature is lower than our body temperature, the skin surface will lose heat to the air

14. Body Temperature Regulation
Body temperature regulation is accomplished by the
Dilation of dermal vessels (to cool)
Constriction of dermal vessels (to warm)
Increasing sweat gland secretions (to cool)

15. Body Temperature Regulation
When at rest in an environment below 31oC (88oF) sweat glands secretions unnoticeable
– ½ Liter per day

16. Body Temperature Regulation
When body temperature rises, sweating becomes noticeable – loss of fluid up to 12 liters in one day!

17. Cutaneous Sensation Cutaneous sensory receptors Part of nervous system
Classified as exteroceptors (because the respond to stimuli outside the body)
Sense touch and pain
Meissner’s corpuscles (in dermal papillae)
Merkel discs

18. Metabolic Functions Synthesis of vitamin D
When sunlight hits the skin, modified cholesterol molecules in dermal blood vessels are converted to vitamin D
Need vitamin D for Calcium metabolism (calcium cannot be absorbed from digestive tract without vitamin D)

19. Metabolic Functions Also several other Chemical conversions such as
the disarming of many cancer-causing chemicals that penetrate the epidermis
Conversion of some harmless chemicals into carcinogens

20. Metabolic Functions Also several other Chemical conversions such as
Activation of some steroid hormones – cortisone cream into hydrocortisone (an anti-inflammatory steroid)
Production of proteins such as collagenase, an enzyme that aids in detering wrinkles

21. Blood Reservoir Can hold 5% of the body’s entire blood volume
When other body organs need a greater blood supply, nervous system constricts dermal blood vessels, pushing more blood into circulation, making more available to those organs

22. Excretion of Wastes
Limited amounts of ammonia, urea, and uric acid is eliminated from the body in sweat
Most of these wastes are eliminated in urine

23. Functions, Homeostatic Imbalances, Burns, Cancer, Development
Chapter 5 c Part 2
Functions, Homeostatic Imbalances, Burns, Cancer, Development

24. Homeostatic Imbalances of Skin
Skin can develop more than 1000 different conditions and ailments
Most common skin disorders are bacterial, viral or fungal infections
Less common, but more damaging are skin cancer and burns

25. Skin Homeostatic Imbalances Infections
Athletes foot
Caused by fungal infection

26. Skin Homeostatic Imbalances Infections
Boils and Carbuncles
Caused by bacterial infection

27. Skin Homeostatic Imbalances Infections
Cold sores
Caused by virus

28. Skin Homeostatic Imbalances Allergies
Contact dermatitis
Exposure causes allergic reactions
Poison Ivy

29. Skin Homeostatic Imbalances Infections
Impetigo
Caused by bacterial infection

30. Skin Homeostatic Imbalances
Psoriasis
Caused is unknown
Triggered by trauma, infection, stress

31. Skin Homeostatic Imbalances
Skin Cancer
Cancer – abnormal cell mass
Skin cancer is the most common type of cancer
Slide 4.29
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32. Cancer Two types Benign Does not spread (encapsulated) Malignant
Metastasized (moves) to other parts of the body

33. Skin Cancer The three major types of skin cancer are:
Basal cell carcinoma
Squamous cell carcinoma
Melanoma
Slide 4.30
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

34. Basal Cell Carcinoma Least malignant
Most common type (90% of all skin cancer)
Arises from the Basal layer
Stratum basale cells proliferate and invade the dermis and hypodermis

35. Basal Cell Carcinoma Slow growing and often does not metastasize
Can be cured by surgical excision in 99% of the cases

36. Squamous Cell Carcinoma
Arises from keratinocytes of the stratum spinosum
Arise most often on scalp, ears, and lower lip
Grows rapidly & metastasizes if not removed
Metastasizes to lymph nodes

37. Squamous Cell Carcinoma
Early removal allows a good chance of cure
Prognosis is good if treated by radiation therapy or removed surgically

38. Malignant melanoma Most deadly of skin cancers
because it is highly metastatic and resistant to chemotherapy

39. Malignant melanoma Cancer of melanocytes
Metastasizes rapidly to lymph and blood vessels
Detection uses ABCD rule

40. ABCD(E) Rule A = Asymmetry Two sides of pigmented mole do not match
B = Border irregularity
Borders of mole are not smooth, it is irregular and exhibits indentations
C = Color
Different colors in pigmented area, black, brown, tan, and sometimes red or blue
Slide 4.32
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

41. ABCD(E) Rule D = Diameter
Spot is larger than 6 mm in diameter (size of a pencil eraser)
E = Elevation
Spot is elevated above the skin surface.

42. Melanoma
Treated by wide surgical excision accompanied by immunotherapy
Chance of survival is poor if the lesion is over 4 mm thick

43. Skin Cancer Most skin tumors are benign and do not metastasize
A crucial risk factor for nonmelanoma skin cancers is the disabling of the p53 gene (tumor suppressor gene) by overexposure to UV radiation in sunlight

45. Burns

46. Skin Homeostatic Imbalances
Burns
Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals
Associated dangers
Dehydration
Electrolyte imbalance
Circulatory shock
Slide 4.25
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

47. 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 5.8a

48. Severity of Burns First-degree burns Only epidermis is damaged
Skin is red and swollen
Pain

49. Severity of Burns Second-degree burns
Epidermis and upper dermis are damaged
Skin is red and swollen with blisters
Pain

50. Severity of Burns Third-degree burns
Entire thickness of the skin is damaged
Burn area appears gray-white, cherry red, or black
No initial edema or pain since nerve endings are destroyed

51. Severity of Burns Fourth-degree burns
Burns extend through the skin to injure muscle, ligaments , tendons , nerves, blood vessels, and bones.

52. 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
Slide 4.28
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

53. Developmental Aspects of the Integument: Fetal
Epidermis develops from ectoderm
Dermis and hypodermis develop from mesoderm

54. Developmental Aspects of the Integument: Fetal
Lanugo – downy coat of delicate hairs covering the fetus during 5th and 6th months
Shed by 7th month when vellus hairs start to appear

55. Developmental Aspects of the Integument: Fetal
Vernix caseosa – a white, cheesy looking substance produced by sebaceous glands that protects the skin of the fetus in the amnion (babies are born with it)

56. Developmental Aspects of the Integument: Fetal
Milia – small white spots on forehead and nose caused by accumulations in sebaceous glands
Disappears by third week after birth

57. Developmental Aspects of the Integument: Adolescent to Adult
Skin and hair become oilier and acne may appear in adolescence
Skin shows the effects of cumulative environmental assaults around age 30
Scaling and dermatitis become more common as we age

58. Developmental Aspects of the Integument: Old Age
Epidermal replacement of cells slows and skin becomes thinner
Skin becomes dry and itchy
Subcutaneous fat layer diminishes, leading to intolerance of cold

59. Developmental Aspects of the Integument: Old Age
Decreased elasticity and loss of subcutaneous tissue leads to wrinkles
Decreased numbers of melanocytes and Langerhans’ cells increase the risk of skin cancer

60. Developmental Aspects of the Integument: Old Age
By 50 the number of active hair follicles is less, and hair thins.
Hair loses its luster
Delayed-action genes responsible for graying and male pattern baldness become active

61. Next time! Study guides up to page 112 checked
Quiz
Next time!
Study guides up to page 112 checked