1. The Integumentary System
Skin and its accessory structures, sweat and oil glands, hair, nails, muscles and nerves

2. Skin A large organ composed of all 4 tissue types 22 square feet
Weight 10 lbs.
7% of total body weight
1.5mm-4mm thick
Two distinct regions
Epidermis
Epithelial cells, avascular
Dermis
Fibrous connective tissue, vascularized

3. SKIN hair shaft stratum corneum epidermis dermal papilla
Meissner’s corpuscle
(touch)
blood vessels
sebaceous gland
arrector pili muscle
dermis
sweat gland
hair follicle
Pacinian corpuscle (deep pressure)
adipose tissue (usually in subcutaneous area)

4. Epidermis Superficial, thinner part of skin
Epithelial tissue- keratinized stratified squamous epithelium
avascular (contains no blood vessels)

5. Overview of Epidermis Stratified squamous epithelium
4 types of cells-Keratinocytes, melanocytes, langerhans cells and merkel cells
5 distinct strata (layers) of cells

6. Cells of Epidermis Keratinocyte 90% of epidermal cells
Produce keratin, fibrous protein that gives skin its protective properties
many desmosomes
Mitosis at basal layer and dead at apical layer
Rub off millions daily, new epidermis every days

7. Cells of Epidermis Melanocyte
Spider-shaped cell that makes pigment Melanin
In deepest layer, sending processes into other layers to deliver melanin
Accumulates melanin in melanosomes that are taken up by keratinocyte
Melanin accumulates on sunny side of keratinocytes creating a pigment shield that protects nucleus from damaging UV radiation

8. Cells of Epidermis Langerhans Cells
Phagocytes that ingest foreign substances and help activate the immune system

9. Cells of Epidermis Merkel Cells
Occasional cells found in deepest layers of epidermis at epidermal-dermal junction
In contact with a disclike sensory nerve ending forming a merkel disc that functions as sensory receptor for touch

11. Several Distinct layers of keratinocytes in various stages of development form epidermis

12. Layers (Strata) of the Epidermis -a continuum of cell growth as move up the layers
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale

13. Stratum Basale (stratum germinativum)
Deepest layer,single layer of mitotically active cells attached to dermis
Youngest keratinocytes
Large nuclei
10-25% of cells are melanocytes
Occasional merkel cells
Desmosomes and hemidesmosomes

14. Stratum Basale
When the germinal portion of the epidermis is destroyed, new skin cannot regenerate with a skin graft.

15. Stratum Spinosum (prickly layer)
8-10 cell layers
Cells held together by desmosomes which gives cells a spiny or irregular appearance during tissue preparation
Langerhans cells present
Projections of melanocytes

16. Stratum Granulosum
Transition between metabolically active strata and the dead cells of the more superficial strata
Thin, 3-5 layers of flat dying cells that show nuclear degeneration and cells flatten
lamellar granules that have a waterproofing glycolipid that gets released into extracellular space to slow water loss from dermis
Contain dark-staining keratohyalin granules that will help form keratin in upper layers

17. Stratum Lucidum
present only in Thick Skin of fingers tips, palms of the hands, and soles of the feet
Three to five layers of clear, flat, dead cells that form a thin translucent band

18. Stratum Corneum Outermost layer ¾ thickness of epidermis
25 to 30 layers of flat dead cells filled with keratin and surrounded by glycolipids
Barrier to light, heat, water, chemicals & bacteria, protect against abrasion and penetration

19. Keratinization and Growth of Epidermis
New cells formed in stratum basale and pushed to surface
Keratinization- accumulate keratin as move up through the layers
Aptosis
Slough
4 week process

20. Dermis
Deeper, thicker part of skin
Strong flexible connective tissue

21. Papillary Dermis Thin superficial layer Top 20% of dermis
Aerolar connective tissue with collagen fibers and fine elastic fibers
Very vascular
Dermal Papillae
Small peg-like projections into epidermis that increase the surface area
Capillary loops
Free nerve endings (pain receptors)
Meissner corpuscles that are touch receptors

22. Reticular Dermis 80% of thickness of Dermis
Dense irregular connective tissue with a matrix of thick bundles of interlacing collagen fibers
Provides strength, extensibility & elasticity to skin

23. Dermis
Epidermal Ridges are downward projections of epidermis into dermis between the dermal papillae of the papillary region creating ridges and grooves that increase friction and enhance grip
Fingerprints and footprints
Genetically determined, unique and do not change throughout life

24. Dermis
Lines of cleavage in the skin/skin tension lines indicate the predominant direction of the underlying collagen fibers.
Important for surgical incision planning
Incision parallel to them provides best scar

26. Blister separation of dermis and epidermis by fluid accummulation

27. Stretch Marks
Tears in dermis
White scars
striae

28. Skin
Callus- abnormal thickening of skin due to exposure to friction

29. Hypodermis AKA subcutaneous layer, subQ, superficial fascia
Not part of the skin
Deep to dermis
Consists of areolar and adipose tissue
Functions to store fat, absorb shock, insulator, anchors skin to underlying structures and contains lamellated (pacinian corpuscles) nerve endings for pressure

30. Basis of Skin Color 3 pigments
Melanin
Only pigment made in skin
Yellow to reddish brown
Synthesis depends on enzyme tyrosinase in melanocytes, UV light increases activity of enzyme
Difference in color due to amount and kind of melanin and not number of melanocytes
Pheomelanin- yellow to red
Eumelanin- brown to black
Freckles and moles are local accumulations of melanocytes
Albinism- inherited inability to produce melanin, melanocytes can not synthesize tyrosinase
Vitiligo is partial or complete loss of melanocytes from patches of skin resulting in irregular white spots due to immune malfunction

31. Basis of Skin Color 3 pigments
Hemoglobin
Oxygen carrying pigment in RBC
In dermal capillaries
Carotene
Yellow to orange pigment found in plant products
Precursor of vitamin A that is used to synthesize pigments needed for vision
Excessive amounts accumulate in stratum corneum and fatty areas of dermis and sub Q, in palms and soles

33. Skin Color and Diagnosis
Cyanotic
Skin of nail beds and mucus membranes bluish due to poorly oxygenated hemoglobin

34. Jaundice
Build up of bilirubin in skin, yellow pigment
Liver disease

35. Erythema
Redness due to engorgement of capillaries of dermis with blood due to injury, heat, infection, inflammation or allergic reactions

36. Pallor
Low blood pressure, shock, anemia

37. Bruises
Black and blue marks due to blood that escapes circulation and clots beneath skin-hematomas

38. Accessory Structures of Skin skin appendages
develop from the embryonic epidermis
Cells sink inward during development to form:
Hair and hair follicles
sebacious (oil) glands
sweat glands
nails

39. Glands of Skin Sebaceous (oil) glands Sudoriferous (sweat) glands
Ceruminous glands

40. Sebaceous(oil) Glands
Secreting portion in dermis
Opens onto the hair follicle
Absent in palms and soles
Secrete sebum
Cells accumulate lipids until they burst, holocrine glands
Sebum is lipids and cell fragments
Softens and lubricates skin and hair, prevents brittleness
bactericidal

41. Sebaceous(oil) Glands
Whiteheads –sebaceous gland duct blocked and sebum accumulates
Blackhead when the material oxidizes or dries
Acne-inflammation of these glands, colonized by bacteria

42. Sudoriferous (sweat) Glands
Release sweat onto hair follicles or onto skin surface through pores
Eccrine
apocrine

43. Eccrine Sweat Glands
Excretory duct ends at pore on surface of epidermis
Most numerous on palms, sole of feet and forehead
Sweat- 99% water, salts, vit C, antibodies, microbe killins peptide, dermicidin and trace metabolic wastes, acidic
Regulated by nervous system
Function to regulate body temperature and eliminate wastes
Insensible sweat and sensible sweat

44. Apocrine Sweat Glands Ducts open to hair follicles
Secretory product like sweat but has lipids and proteins, odorless but takes on odor when organic molecules decomposed by bacteria on skin
Axillary and anogenital areas
Function at puberty but precise function not known and no role in thermoregulation

45. Ceruminous Glands Modified apocrine sweat glands in external ear
Produce a waxy substance
Cerumen-earwax is combined secretion of ceruminous glands and sebaceous glands, deters insects and blocks entry of foreign materials

46. Hair
Hair is columns of dead keratinized cells bonded together by extracellular proteins
On entire skin surface except palms, soles, lips, nipples and parts of external genitalia
Shaft-portion that project above skin surface
Root-embedded in skin, penetrates into dermis or subQ
Hair Follicle- surrounds the root
Bulb-base of hair follicle

47. Structure of Hair Shaft – visible Root -- below the surface
Follicle surrounds root
base of follicle is bulb
blood vessels
Mitotically active cells

48. Structure of Hair Follicle
About 4mm below skin surface, expanded bulb
Knot of sensory nerve endings called hair follicle receptor or hair root plexus wrap around the bulb and are stimulated by bending of hairs, hairs sensitive to touch

49. Hair Follicle
Papilla of hair-dermal tissue that protrudes into hair pulp and contains capillaries
Matrix- actively dividing cells
Figure 5.5c

50. Structure of Hair Shaft – visible
3 concentric layers of keratinized cells
Medulla
Central core, large cells and air spaces
Cortex
Bulky layer around medulla, several layers of flattened cells
Cuticle
Outermost layer, single layer of cells that overlap one another from below like roof shingles

51. Figure 5.5a, b

53. Hair Pigment
Hair pigment made by melanocytes at base of hair follicle and transferred to cortical cells

54. Hair Color
Hair color is due primarily to the amount and type of melanin.
Graying of hair occurs because of a progressive decline in tyrosinase.
Dark hair contains true melanin
Blond and red hair contain melanin with iron and sulfur added
Graying hair is result of decline in melanin production
White hair has air bubbles in the medullary shaft

55. Hair Related Structures
Arrector pili
smooth muscle in dermis contracts with cold or fear.
forms goosebumps as hair is pulled vertically, into upright position
Hair root plexus
detect hair movement
sebaceous (oil) glands

56. Hair Growth
The hair growth cycle consists of a growing stage and a resting stage.
Growth cycle = growth stage & resting stage
Growth stage
lasts for 2 to 6 years
matrix cells at base of hair root producing length
Resting stage
lasts for 3 months
matrix cells inactive & follicle atrophies
Old hair falls out as growth stage begins again
normal hair loss is 70 to 100 hairs per day
With age, hair not replaced as fast as shed leading to thinning and baldness(alopecia)
Both rate of growth and the replacement cycle can be altered by illness, diet, high fever, surgery, blood loss, severe emotional stress, and gender.
Chemotherapeutic agents affect the rapidly dividing matrix hair cells resulting in hair loss.

57. Functions of Hair Decreases sunburn Eyelashes help protect eyes
Prevents heat loss
Decreases sunburn
Eyelashes help protect eyes
Touch receptors (hair root plexus) senses light touch

59. Nails
Plates of tightly packed, hard, dead keratinized epidermal cells that form a clear, solid covering over the dorsal surfaces of the distal portions of digits

60. Nail body-visible portion of nail
Free Edge- part that extends past distal aspect of digit
Hyponychium- region below free edge
Nail Root- proximal part buried beneath nail fold
Lunula-white crescent, too thick to see vasculature
Eponychium- cuticle

63. TYPES OF SKIN Thin skin Thick skin (0.6 to 4.5 mm)
covers all parts of the body except for the palms and palmar surfaces of the digits and toes.
lacks epidermal ridges
has a sparser distribution of sensory receptors than thick skin.
Thick skin (0.6 to 4.5 mm)
covers the palms, palmar surfaces of the digits, and soles
features a stratum lucidum and thick epidermal ridges
lacks hair follicles, arrector pili muscles, and sebaceous glands, and has more sweat glands than thin skin.

64. Skin Cancer The three major types of skin cancer are:
Basal cell carcinoma
Squamous cell carcinoma
Melanoma
Basal cell and Squamous cell considered nonmelanoma skin cancers. In 2008, more than 1,000,000 new cases in US but less than 1,000 deaths.

65. Basal Cell Carcinoma Least malignant and most common skin cancer
cells at base of epidermis proliferate and invade the dermis and hypodermis
Sun-exposed areas
Dome-shaped nodules that develop a central ulcer with a pearly, beaded edge
Slow growing and do not often metastasize
Can be cured by surgical excision in 99% of the cases

66. Basal Cell Carcinoma

67. Basal Cell Carcinoma Three common presentations:
Small, smooth, pale, or waxy shiny lump
Firm, red lump
A lump that bleeds or develops a crust

68. Basal Cell Carcinoma

69. Squamous Cell Carcinoma
Arises from cells of epidermis
Arise most often on scalp, ears, and lower lip
Scaly reddened papule
Grows rapidly and metastasizes if not removed
Prognosis is good if treated

70. Squamous Cell Carcinoma

71. Squamous Cell Carcinoma

72. Melanoma
Cancer of melanocytes is the most dangerous type of skin cancer because it is:
Highly metastatic
Resistant to chemotherapy

74. Melanoma
A form of skin cancer that arises in melanocytes, the cells that produce pigment and also are found in the epidermis.
Melanomas usually begin in a mole, which is a benign cluster of melanocytes and other tissue.
Normal
moles:

75. Signs and Symptoms of Melanoma
Change in the size, shape or color of a mole, such as:
Signs that a mole’s border is becoming more ragged
Spread of pigmentation beyond its border
Scaliness, bleeding or change in the appearance of a bump or nodule
Change in sensation, itchiness, tenderness or pain in a mole or other growth \

76. Use ABCD Rule to Spot Melanoma
A (Asymmetry) one portion of the mole does not match the other
B (Border) edges are irregular, notched, or blurred
C (Color) different shades of black or brown, patchy colors
D (Diameter) spot is 6 millimeters across, or growing larger A B C D

77. Melanoma (the A-B-C and Ds)
Asymmetry -- The shape of one half does not match the other.

78. Asymmetry One half does not match the other half.

79. Border irregularity The edges are ragged, notched, or blurred.

80. Melanoma (the A-B-C and Ds)
Color -- The color is uneven. Shades of black, brown, and tan may be present. Areas of white, grey, red, pink, or blue also may be seen.

81. Melanoma (the A-B-C and Ds)
Diameter -- There is a change in size, usually an increase. Melanomas are usually larger than the eraser of a pencil (5 mm or 1/4 inch).

82. Diameter -Greater than ¼ inch
Diameter -Greater than ¼ inch. Any sudden or continuing increase in size is of special concern.

83. Normal Mole

84. Malignant Mole

85. Melanoma May be found when a pre-existing mole changes: Early changes
- forming a new black area
- newly formed fine scales
- itching in a mole
More advanced changes
- texture changes (becomes hard or lumpy)
- itch, ooze, or bleed
- usually do not cause pain

86. Melanoma
Moles are clusters of melanocytes, called nevus (singular) and nevi (multiple)
Most people have that appear at birth or after birth, usually before age 40
Increased risk of melanoma in those with more than 50 or in person with dysplastic nevi (abnormal looking moles)

87. Melanoma US- more than 53,600 people learned they had melanoma in 2008
Risk factors:
Fair skin
More than 50 moles
Dysplastic moles
About 10% of patients with melanoma have a family history
Depressed immune system
UV radiation
Blistering sunburn

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

89. Wear your Sunblock!!!

90. Burns
Tissue damage from excessive heat, electricity, radioactivity, or corrosive chemicals that destroys (denatures) proteins in the exposed cells is called a burn.
Generally, the systemic effects of a burn are a greater threat to life than are the local effects.
The seriousness of a burn is determined by its depth, extent, and area involved, as well as the person’s age and general health. When the burn area exceeds 70%, over half of the victims die.

91. Burns First-degree – only the epidermis is damaged
Symptoms include localized redness, swelling, and pain
Second-degree – epidermis and upper regions of dermis are damaged
Symptoms mimic first degree burns, but blisters also appear
fluid-filled blisters separate epidermis & dermis
Heals in 3 to 4 weeks & may scar

92. Burns Third-degree – entire thickness of the skin is damaged
Burned area appears gray-white, cherry red, or black; there is no initial edema or pain (since nerve endings are destroyed)

93. Burns Destruction of proteins of the skin Problems that result
chemicals, electricity, heat
Problems that result
shock due to water, plasma and plasma protein loss
circulatory & kidney problems from loss of plasma
bacterial infection

94. Burns

95. Rule of Nines Estimates the severity of burns
Burns considered critical if:
Over 25% of the body has second-degree burns
Over 10% of the body has third-degree burns
There are third-degree burns on face, hands, or feet

96. Rule of Nines
Figure 5.8a

97. Wound Healing Two types depending on the depth of the wound
Epidermal Wound Healing
Deep Wound Healing

98. Epidermal Wound Healing
Abrasion or minor burn
Basal cells migrate across the wound
Contact inhibition with other cells stops migration
Epidermal growth factor stimulates basal cells to divide and replace the ones that have moved into the wound
Full thickness of epidermis results from further cell division

99. Deep Wound Healing
In response to an injury that extends into the dermis and subQ
Scar tissue is formed
Four Phases
Inflammatory
Migratory
Proliferative
Maturation

100. Deep Wound Healing
When an injury extends to tissues deep to the epidermis, the repair process is more complex than epidermal healing, and scar formation results.
Healing occurs in 4 phases
inflammatory phase has clot unite wound edges and WBCs arrive from dilated and more permeable blood vessels
migratory phase begins the regrowth of epithelial cells and the formation of scar tissue by the fibroblasts
proliferative phase is a completion of tissue formation
maturation phase sees the scab fall off
Scar formation
hypertrophic scar remains within the boundaries of the original wound
keloid scar extends into previously normal tissue
collagen fibers are very dense and fewer blood vessels are present so the tissue is lighter in color

101. Age Related Structural Changes
Collagen fibers decrease in number & stiffen
Elastic fibers become less elastic
Fibroblasts decrease in number
decrease in number of melanocytes (gray hair, blotching)
decrease in Langerhans cells (decreased immune responsiveness)
reduced number and less-efficient phagocytes

102. AGING AND THE INTEGUMENTARY SYSTEM
Most of the changes occur in the dermis
wrinkling, slower growth of hair and nails
dryness and cracking due to sebaceous gland atrophy
Walls of blood vessels in dermis thicken so decreased nutrient availability leads to thinner skin as subcutaneous fat is lost.