Chapter 4 - Skin and Body Membranes

Anatomy and Physiology - Chapter 4 - Skin and Body Membranes

1. CHAPTER 4 SKIN AND BODY MEMBRANES

2. Body Membranes Body membranes cover surfaces, line body cavities, and form protective sheets around organs Fall into two major groups: 1. epithelial membranes include cutaneous, mucous, and serous membranes 2. connective tissue membranes Represented by synovial membranes

3. Body Membranes The functions of body membranes: 1. line or cover body surfaces 2. protect body surfaces 3. lubricate body surfaces

4. CLASSIFICATION OF BODY MEMBRANES

5. Epithelial Membranes Epithelial membranes (covering and lining membranes) include cutaneous membrane, mucous membranes, and serous membranes

6. Epithelial Membranes Calling these “epithelial” is inaccurate Do contain an epithelial sheet, but it is always combined with an underlying layer of connective tissue These are simple organs

7. Cutaneous Membranes Cutaneous Membrane : your skin Exposed to air Dry membrane The superficial epidermis keratinizing stratified squamous epithelium The underlying dermis mostly dense connective tissue

8. Mucous Membranes Surface epithelium type depends on site Underlying loose connective tissue (lamina propia ) Lines all body cavities that open to the exterior body surface Often adapted for absorption and secretion

9. Serous Membranes Surface simple squamous epithelium Underlying areolar connective tissue Lines open body cavities that are closed to the exterior of the body Serous layers separated by serous fluid

10. Serous Membranes Specific serous membranes Peritoneum Abdominal cavity Pleura Around the lungs Pericardium Around the heart

11. Connective Tissue Membranes Synovial membrane Connective tissue only Lines fibrous capsules surrounding joints Provide: Smooth surface Secrete lubricating fluid

12. Synovial Membrane

13. Connective Tissue Membranes Synovial membrane Also line bursae and tendon sheaths Cushion organs moving against each other during muscle activity

14. THE INTEGUMENTARY SYSTEM (SKIN)

15. Integumentary System Skin (cutaneous membrane) Skin derivatives Sweat glands Oil glands Hairs Nails

16. Skin Functions Protects deeper tissues from: Mechanical damage Chemical damage Bacterial damage Thermal damage Ultraviolet radiation Desiccation

17. Skin Functions The uppermost layer of the skin is full of keratin and is cornified , or hardened, to help prevent water loss from the body surface

18. Skin Functions Protects deeper tissues Aids in heat regulation Capillary network and sweat glands Aids in excretion of urea and uric acid Urea, salts, water Synthesizes Vitamin D Modified cholesterol molecules in the skin are converted to Vitamin D by sunlight Cutaneous Sensory Receptors Tiny sensors detect touch, pressure, temperature and pain

19. Skin Structure Epidermis – outer layer Stratified squamous epithelium Often keratinized Dermis Dense connective tissue

20. Skin Structure

21. Skin Structure Epidermis and dermis are firmly connected A burn or friction may cause them to separate Interstitial fluid accumulates, forms blister

22. Skin Structure Deep to the dermis is the hypodermis (subcutaneous tissue) Not part of the skin Anchors skin to underlying organs Composed mostly of adipose tissue

23. Skin Structure

24. EPIDERMIS

25. Epidermis Composed of up to five layers: Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum

26. Epidermis Most cells of the epidermis are keratinocytes : keratin cells

27. Epidermis – Stratum basale Deepest cell layer in epidermis Lies closest to the dermis Receive the most nourishment, through diffusion, from the dermis Cells are undergoing mitosis (also called the stratum germinativum ) Pushed upward from this layer

28. Epidermis – Stratum basale

29. Epidermis – stratum spinsosum and stratum granulosum Above the stratum basale is the stratum spinosum and then the stratum granulosum Flatter, more keratinized

30. Epidermis – Stratum lucidum Above the stratum granulosum is the stratum lucidum Clear layer full of dead skin cells Not present in all skin regions Thick, hairless areas (palms, soles) High in keratin Far from blood supply

31. Epidermis – Stratum corneum Outermost layer Accounts for ¾ of epidermal thickness Shingle-like dead cells Completely filled with keratin Also called cornified or “horny cells”

32. Epidermis – stratum corneum The stratum corneum rubs and flakes off slowly as dandruff The stratum corneum is replaced quickly by rising cells from the stratum basale We have an entirely new epidermis every 25-45 days.

33. Epidermis - Melanin Melanin : pigment that ranges in color from yellow to brown to black Melanin is produced by melanocytes Found mainly in the stratum basale Accumulates in membrane-bound granules called melanosomes

34. Epidermis - Melanin The amount of melanin in the epidermis results from genetics and sunlight exposure Freckles and moles are seen in areas where melanin is concentrated

35. DERMIS

36. Dermis Dermis – your hide Two layers: Papillary Layer (upper region) Reticular Layer (lower region)

37. Dermis – Papillary Layer Dermal Papillae Indent epidermis above Create fingerprints Capillary loops Nourish epidermis Pain and touch receptors Pain – free nerve endings Touch – Meissner’s corpuscles

38. Dermis – Reticular Layer Blood vessels Sweat and oil glands Deep pressure receptors – Pacinian corpuscles Contain phagocytes that prevent bacteria from reaching deeper tissues

39. Dermis Heavy in collagen and elastic fibers As age increases, these fibers decrease as do fat cells and skin sags Abundantly supplied with blood Skin reds and warms with high body temp Rich nerve supply

40. SKIN COLOR

41. Skin Color Three pigments contribute to skin color: 1. the amount and kind of melanin 2. the amount of carotene in the stratum corneum and subcutaneous tissue 3. the amount of hemoglobin in the dermal blood vessels

42. Skin Color People with a lot of melanin have brown-toned skin People with less melanin have fair-toned skin

43. Skin Color The hemoglobin in the dermal blood supply shows through the transparent cell layers above This gives skin a rosy glow

44. Skin Color Emotions also influence skin color, and many alterations in skin color signal disease: 1. Redness ( erythema ) – reddened skin Blushing, fever, hypertension, inflammation, allergy

45. Skin Color 2. Pallor (blanching) Emotional stress (fear, anger) Anemia, hypotension, impaired blood flow 3. Jaundice (yellowing) Liver/Gallbladder disorders – excess of bilirubin in the blood

46. Skin Color 4. Bruises (black and blue coloring) Show where blood has escaped circulation and has clotted in tissue spaces Hematomas An unusual tendency to bruising may signify a deficiency of vitamin C or hemophilia

47. Skin appendages

48. Skin appendages Skin appendages : skin-associated structures that serve a particular function Functions include sensation, contractility, lubrication and heat loss

49. Skin Appendages Skin appendages include cutaneous glands, hair and hair follicles, nails Arise from the epidermis Play a role in homeostasis

50. Cutaneous Glands Exocrine glands Release secretions to the skin surface via ducts Two groups: Sebaceous glands Sweat glands Formed in the stratum basale and push into the deeper layers of the dermis

51. Sebaceous Glands Oil glands Found all over skin except palms and soles Sebum : the product of sebaceous glands Lubricate skin Kills bacteria Most with ducts empty into hair follicles Increase production during puberty

52. Sweat Glands Also called sudoriferous glands Widely distributed across the skin Two types: 1. eccrine Open via duct to pore on skin Produce sweat Important in heat regulation 2. apocrine Usually larger than eccrine glands Ducts empty into hair follicles Activated during pain and stress

53. Sweat Glands

54. Sweat and its Function Composition: Mostly water Some metabolic wastes (ammonia, urea, etc.) Fatty acids and proteins ( apocrine only) Function: Helps dissipate excess heat Excretes waste products Acidity decreases bacterial growth Odor is from associated bacteria

55. Hair and Hair Follicles Produced by hair bulb Formed by well-nourished stratum basale cells in the matrix (growth zone) Consists of hard, keratinized epithelial cells Melanocytes provide pigment for hair color

56. Hair and Hair Follicles

57. Hair Anatomy Central medulla Cortex surrounds medulla Cuticle on outside of cortex Most heavily keratinized

58. Hair structures Hair follicle Dermal and epidermal sheath surround hair root Arrector pili Smooth muscle Cause hair to stand up Goosebumps ( piloerection ) Sebaceous gland Lubricates hair Sweat gland

59. Hair function Warmth Limited in humans Protection Touch sense Non-verbal communication (eyebrows and eyelashes)

60. Human Body Hair Types According to forensic scientists there are six types of hair on the human body: Head Eyebrow and eyelash Beard and moustache Body hair ( Auxilairy ) Pubic Armpit

61. Nails Scale-like modifications of the epidermis Highly keratinized Stratum basale extends beneath the nail bed Responsible for growth Lack of pigment makes them colorless

62. Nail Structures Free Edge Body Root of Nail Eponychium : proximal nail fold that projects into the nail body

63. SKIN HOMEOSTATIC IMBALANCES

64. Infections Athlete’s Foot Medically known as tinea pedis Caused by a fungal infection Thrives in warm, moist areas Contagious by contact

65. Infections Boils and Carbuncles Inflammation of hair follicles and sebaceous glands Caused by bacterial infection

66. Infections Cold sores Caused by the Herpes Simplex Virus Can remain dormant for extended periods of time

67. Infections Impetigo Caused by bacterial infection (staph) Highly contagious Common in elementary children

68. Allergies Contact dermatitis Exposure to substance causes an allergic reaction Ex. poison ivy

69. Allergies Psoriasis Chronic, autoimmune condition Can be disfiguring Attacks are often triggered by trauma, infection, stress or hormonal changes

70. BURNS

71. Burns Burn : tissue damage and cell death caused by heat, electricity, UV radiation (sunburns) or chemicals

72. Burns Immediate Associated Dangers: 1. Dehydration 2. Electrolyte Imbalance 3. Circulatory Shock

73. Burns – Rule of Nines Way of determining the extent of burns (how much of the body is burned) Body is divided into 11 areas for quick estimation Each area represents about 9% of the body (last 1% is the area surrounding the gentials )

74. Burns – Rule of Nines

75. Burns - Severity First-Degree Second – Degree Third-Degree

76. Burns - Severity

77. 1 st degree burns Only the epidermis is damaged (superficial) Skin is red and swollen No blistering Minimal pain Usually heals in a week or less Cool, cover loosely, over the counter pain medications

78. 1 st degree burns

79. 2 nd degree burns Epidermis and upper dermis are damaged (partial thickness) Skin is red Blisters that sometimes break Severe pain Takes up to a month to heal Cool, cover loosely, over the counter pain meds Be cautious of infections

80. 2 nd degree burns

81. 3 rd degree burns Destroy entire skin layer (full thickness) Skin is gray-white or black; may appear waxy of charred Minimal pain at first due to nerve damage Partial or complete skin grafts, biomask , amnion Possible system shock and cardiac or respiratory arrest Extended healing time

82. 3 rd degree burns

83. 3 rd degree burn treatment

84. Critical Burns Burns are considered critical if: Over 25% of the body has 2 nd degree burns Over 10% of the body has 3 rd degree burns There are third degree burns of the face, hands or feet

85. Critical Burns Facial burns Particularly dangerous Possibility of burns in respiratory passage Can cause swelling and suffocation Joints Scar tissue can limit mobility

86. SKIN CANCER

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

88. Skin Cancer Types Basal Cell Carcinoma Least malignant Most common type Arises from stratum basale

89. Skin Cancer Types Squamous Cell Carcinoma Arises from stratum spinosum Metastasizes to lymph nodes Early removal allows for a good chance of a cure

90. Skin Cancer Types Malignant Melanoma Most deadly type of skin cancer Cancer of melanocytes Metastasizes rapidly to lymph and blood vessels Detection uses ABCD rule

91. ABCD Rules

92. ABCD Rules A = Asymmetry Two sides of pigmented mole do not match B = Border Irregularity Borders of mole are not smooth

93. ABCD Rules C = Color Different colors in pigmented area D = Diameter Spot is larger than 6mm in diameter

94. ABCD Rules