1. Chapter 6 Skin and the Integumentary System
Composed of several tissues
Maintains homeostasis
Protective covering
Retards water loss
Regulates body temperature
Houses sensory receptors
Contains immune system cells
Synthesizes chemicals
Excretes small amounts of waste

2. Physiology of Skin Regulate body temperature Protection
Sweat & change of blood flow toward surface of skin
Protection
From abrasions, bacteria, dehydration, and ultra violet radiation
Reception of Stimuli
Nerve endings specifically designed for pressure, temperature, touch and pain

3. Physiology of Skin Excretion Synthesis of Vitamin D Immunity
sweat helps reduce levels of water, salts, and other organic compounds
Synthesis of Vitamin D
Helps manufacture vitamin D
Helps body absorb calcium and phosphorus from food
Immunity
Certain cells help in your ability to produce antibodies

4. Skin Cells
Help produce Vitamin D needed for normal bone and tooth development
Some cells (keratinocytes) produce substances that simulate development of some WBCs

5. Layers of Skin Epidermis Dermis Subcutaneous layer beneath dermis
not part of skin

6. Subcutaneous Layer hypodermis loose connective tissue adipose tissue
insulates
major blood vessels

8. Epidermis lacks blood vessels keratinized
thickest on palms and soles ( mm)
melanocytes provide melanin
rests on basement membrane
stratified squamous

10. Epidermal Cells Keratinocyte Melanocyte Produce keratin (protein)
Found at base of epidermis
Produces melanin
Responsible for skin color and absorption of UV radiation

11. Epidermal Cells Langerhan’s cells Granstein cells
Interact with helper T-cells of the immune system
Granstein cells
Resistant to UV radiation
Interact with other T-cells of immune system

12. Epidermis Layers of Epidermis stratum corneum stratum lucidum
stratum granulosum
stratum spinosum
stratum basale

13. Epidermal Layers Stratum Basale Deepest layer
Single layer of cells capable of continued cell division
Also called the stratum germinativum
Cells may migrate to the dermis to become glands and hair follicles
Areas with no hair contain nerve endings that are sensitive to touch (tactile disc)

14. Epidermal Layers Stratum Spinosum Stratum Granulosum
8 to 10 rows of close fitting cells
Surface of the cells contain spine-like projections that help to join cells together
Stratum Granulosum
3 to 5 rows flattened cells that contain dark stained granules of keratohyalin, which is involved in the first steps of keratin formation
Cells start to die in this layer

15. Epidermal Layers Stratum Lucidum Stratum Corneum
Found only in thick skin of palms, and the soles of your feet
3 to 5 rows of clear, flat, dead cells
Stratum Corneum
25 to 30 rows of keratinized cells
Continuously replaced and shed

17. Dermis on average 1.0-2.0mm thick contains dermal papillae
binds epidermis to underlying tissues
irregular dense connective tissue
muscle cells
nerve cell processes
specialized sensory receptors
blood vessels
hair follicles
glands

18. Dermal Layers Papillary Layer Upper 1/5 of the dermis Dermal papillae
Finger-like projections that increase surface area
Projections that extend into the epidermis and may contain blood vessels or
Meissner’s corpuscles- endings that are sensitive to touch
Cause ridges in the overlying epidermis (fingerprints)

19. Dermal Layers Reticular layer
Formed by closely packed irregularly arranged connective tissue
Glands, hair, and nerves fill spaces between
Provides the skin with its strength and elasticity
Attached to underlying organs by the subcutaneous layer
Pacinian Corpuscles
Located in the subcutaneous layer
Nerve endings that are sensitive to pressure

20. Hair Follicles epidermal cells tube-like depression
extends into dermis
hair root
hair shaft
hair papilla
dead epidermal cells
melanin
arrector pili muscle

21. Hair Protects, guards scalp from the sun, eyes from foreign particles
Hair in the ear and nose protect these structures from foreign particles and insects that might be inhaled or crawl into the ear

22. Anatomy of the Hair Shaft
Superficial portion that most of which projects above the skin
Made up of 3 parts
Medulla
inner portion that contains air spaces
Cortex
Middle portion that makes the majority of the hair shaft
Contains pigment granules of dark hair & mostly air in light hair
Cuticle
Outer most layers
Cells heavily keratinized
Arranged like upside-down shingles

23. Anatomy of the Hair Root Hair follicle
Portion that penetrates the dermis and even the subcutaneous layer
Contains the 3 portions like the shaft
Hair follicle
Surrounds the root
Continuation of the stratum basale and stratum spinosum layers of the epidermis
Base of each follicle enlarges and looks like an onion shaped bulb

24. Anatomy of the Hair Papillae of the hair
Indentation of the bulb that is filled with loose connective tissue and many blood vessels

26. Associates of the Hair Complex
Sebaceous (oil) glands
Found in association with hair follicles except on the lips and eyelids
Secrete sebum
Mixture of fats, cholesterol, proteins, and inorganic salts
Function
Prevents hair from becoming brittle
Forms a film that prevents excess evaporation of water from the skin
Keeps the skin soft and flexible
Inhibits the growth of certain bacteria

27. Sebaceous Glands holocrine glands secrete sebum
usually associated with hair follicles
holocrine glands
secrete sebum
absent on palms and soles

28. Clinical Application: Sebaceous Glands
Blackheads
Sebaceous glands enlarge due to accumulated sebum
Color of blackhead is due to melanin and oxidized oil, not dirt

29. Associates of the Hair Complex
Sudoriferous Glands
Divided on basis of structure and location
3 types
Apocrine
Located in axilla and pubic region
Excretory duct open to hair follicles
Start to function at the onset of puberty
Emit an odor
Eccrine
More common
Ducts open to the surface of the skin

30. Associates of the Hair Complex
Both Apocrine and Eccrine glands secrete:
Perspiration
mixture of water, salts (NaCl), urea, uric acid, amino acids, ammonia, sugar, lactic acid and ascorbic acid
Function:
Reduces body temperature by evaporation
Elimination of waste

31. Sweat Glands sudoriferous glands widespread in skin
originates in deeper dermis or hypodermis

32. Associates of the Hair Complex
Mammary glands
Modified sudoriferous glands
Reproductive unit
Ceruminous glands
Found in external auditory meatus
Produce ear wax that protect your ears from foreign particles

33. Nails
protective coverings
nail plate/nail body
nail bed
lunula

34. Nails Average growth is about 1 mm per week
Protect the end of the digits and aid the manipulation of small objects
4 parts of the nail
Free edge- extends past distal end of the digit
Body- majority of the visible nail
Lunula- semilunar white part of the body
Nail Root- hidden part of the nail that lies above the nail matrix
Nail Matrix- functions to bring the growth of nails
when superficial cells become nail cells, push the whole nail across the nail bed

35. Regulation of Body Temperature

38. Problems in Temperature Regulation
Hyperthermia – abnormally high body temperature
Hypothermia – abnormally low body temperature

39. Skin Color Genetic Factors Physiological Factors
varying amounts of melanin
varying size of melanin granules
albinos lack melanin
Physiological Factors
dilation of dermal blood vessels
constriction of dermal blood vessels
accumulation of carotene
jaundice
Environmental Factors
sunlight
UV light from sunlamps
X rays
darkens melanin

40. Skin Color
Melanin
Pigment found primarily in the basale and spinosum epidermal layers
Varies skin color from yellow to black
Number of melanocytes about the same for all races
Skin color due to amount of pigment melanocytes produce

41. Skin Conditions Albinism Vitiligo Freckles Tanning
inability to produce melanin
Vitiligo
loss of melanocytes from an area of skin
Freckles
patches of melanin
Tanning
Also associated with the melanin
Ultra-violet radiation increases melanocyte activity

43. Skin Color Carotene Capillaries Found in the stratum corneum
People of Asian origin have carotene in fatty areas of the dermis
Gives a yellowish hue to the skin
Capillaries
cause the skin to have a pink appearance

44. Epidermal Wound Healing
Common skin wounds
Abrasions
portions of the skin has been scraped away
Laceration
irregular tear of the skin
Puncture
hole “popped” through the skin
Incisions
clean out through the skin
Contusion (bruise)
Tissue below skin damaged
skin is not broken

45. Epidermal Wound Healing
Superficial Wound Healing
Basale cells in the area of the wound break contact with the basement membrane that connects the epidermis to the dermis
2. Basale cells enlarge and migrate across the wound

46. Epidermal Wound Healing
Contact inhibition stops the migrating cells and turns cells in a new direction continues until cells are surrounded by similar cells
Malignant (cancer) cells don’t follow the same rules
continue to spread and invade other areas

47. Epidermal Wound Healing
4. When the “floor” of the wound is covered
Cells divide to form new strata (layers)
This thickens the epidermis and fills in the wound from the bottom upward
5. If a scab was formed, it will fall off when the new epidermis is thick enough to protect itself

48. Healing of Cuts

49. Deep Wound Healing When the injury extends past the epidermis
Commonly due to accidental lacerations of surgical incisions
Scar formation will occur
Repair more complex (4 stages)

50. Deep Wound Healing Inflammatory phase
Inflammation-vascular and cellular response to rid wound of dirt, infection, etc
Blood clot forms to keep the edges of the wound close together
Epidermal cells start to migrate
Vasodilation floods the areas with phagocytic cells and fibroblast

51. Deep Wound Healing 2. Migratory phase
Clot becomes scab and epithelial cells continue migrating to bridge the wound
Fibroblast synthesize scar tissue
Damaged blood vessels begin to re-grow

52. Deep Wound Healing 3. Proliferative Phase
Epithelial cells grow under the scab
Collagenous scar tissue is deposited
Continued blood vessel growth

53. Deep Wound Healing 4. Maturation Phase Scab falls off
Collagenous fibers become more organized
Blood vessels restored to normal
Scar tissue
Dense blood vessels
May not contain hair, glands, or sensory receptors

54. Healing of Burns First degree burn superficial partial-thickness
Dermal blood vessels dilate causing skin to warm and redden
Mild edema (swelling)
Surface layer sometimes shed
Heals in a few days to 2 weeks

55. Healing of Burns Second degree burn deep partial-thickness
Damages epidermis and some dermis
Fluid escapes damaged capillaries causing blisters
Healing depends on stem cells derived from epidermis but located deep within dermis

56. Healing of Burns Third degree burn autograft homograft full-thickness
Skin becomes dry, leathery
Red, black, white color
autograft
Thin layer of skin taken from unburned area & transplanted
homograft
Cadaver skin used to cover burn
Temporary for protection of underlying tissue and prevents infection
various skin substitutes
Amniotic membrane
Artificial membranes composed of silicone, polyurethane, or nylon
Cultured epithelial cells

57. Healing of Burns

58. Rule of Nines
Divides skin surface into regions, each accounting for 9% (or some multiple of 9%) of the total surface area
Important for planning to replace body fluids and electrolytes

59. Rule of Nines

60. Life Span Changes Melanin production slows Skin becomes scaly
Hair thins
Number of hair follicles decrease
Nail growth becomes impaired
Sensory receptors decline
Body temperature unable to be controlled
Diminished ability to activate Vitamin D
Skin becomes scaly
Age spots appear
Epidermis thins
Dermis becomes reduced
Loss of fat
Wrinkling
Sagging
Sebaceous glands secrete less oil

61. Clinical Application Maglignant Melanoma Cancer of the melanocytes
Often caused from overexposure to ultra-violet light of the sun
Most tumors involve basale cells, so they can be removed surgically

62. Clinical Application Malignant Melanoma Best treatment is prevention
Examine your skin for moles that develop irregular appearance
Uneven surfaces or a mixture of colors or change in size or start to bleed
Many of these may be a sign of developing melanoma

63. Clinical Application Wrinkles Collagen fibers Elastic Fibers
stiffens, break apart and form a shapeless tangle
Elastic Fibers
some elasticity, thicken and fray
Subcutaneous
decreases
Sebaceous glands
atrophy leads to dry, cracked skin

64. Clinical Application Melanocytes
Decrease of functioning melanocytes lead to gray hair and atypical skin pigmentation
Increase of size of some melanocytes can cause liver spots
Older skin is more susceptible to pathological conditions like cancer and senile pruritis (itching)

66. Clinical Application Acne Vulgaris most common skin disorder
sebum and epithelial cells clog glands
produces whiteheads and blackheads (comedones)
anaerobic bacteria trigger inflammation (pimple)
largely hormonally induced
androgens stimulate sebum production
treatments include antibiotics, topical creams, birth control pills

67. Clinical Application Cystic Acne Scarring as a result of severe acne
Surrounding epidermal cells might be replaced by connective tissue
Squeezing, pinching or scratching the lesion will increase the chance of developing cystic acne

68. Clinical Application Psoriasis
Symptoms are distinct, reddish, small round skin elevations covered with scales
Caused by abnormally high rate of epidermal cell mitosis
Trauma, infection, stress, seasonal or hormonal changes can irritate
Treatments include steroid ointments and natural sunlight (ultra-violet light)

69. Clinical Application Sunburn
Dead layers of cells peel off and leave unprotected layers of cells
Ultra-violet rays of sunlight damage the cells’ DNA and RNA