1. The Integumentary System
Chapter 4

2. Overview of the Integumentary System
Guiding Question: What are the components of the integumentary system?
Cells and tissues associated with the skin.

3. Overview of the Integumentary System
Not just a covering for the body
Largest organ
Blood vessels, connective tissue structures, glands, hair, nails, nerves, skin
Plays a large role in homeostasis
Has inherent and adaptive characteristics
Calluses
Darken in sun
Elasticity
Sensitive to moisture
Inherent = characteristics determined by genes BUT adaptive = flexibility designed into the genetics of the cells.

4. The Integumentary System
Guiding Questions: 1.) What embryonic layers form the integumentary system? 2.) Describe the development of the integumentary system. 3.) What are some various causes of hair loss?

5. Development of the Integumentary System
Ectoderm & mesoderm in origin
Skin is a complex structure
Many things can go wrong in its development
Let’s make a timeline!

6. 4 weeks: Simple ectoderm epithelium over mesenchyme
outermost layer of skin form a simple squamous tissue that becomes stratified as the embryo develops from the ectoderm

7. 4-5 weeks
Deeper parts of skin begin to form from mesoderm (dermis, hypodermis)

8. 8-9 wks: mesenchyme begins to mature and fibroblasts form, and dents occur in the upper squamous layer
form lanugo.

9. 10 weeks: ridges form between the outer and inner layers of skin—so don’t separate when rubbed
11 weeks: small nails at the tips of fingers & toes, followed by development of special blood vessels in the layers of skin
Angiogenic factors stimulate the production of these vessels

10. 20 weeks: Glandular structures form
Inward growths of the outermost squamous cell layer
Will eventually produce oils and sweat
25 weeks: Pigmentation

11. About 26 weeks: melanoblasts mature into melanocytes (build pigments)
nervous tissue structures develop
Mesenchyme: embryonic connective tissue composed of star-shaped cells in the gel-like matrix or extracellular material.
Fibroblasts: secretes collagen fibers that strengthen the delicate tissue
***Have students create a timeline of skin development. One color card has the # of weeks and a second color card has the development that occurs. They match & put in order. May not need to show this slide…Or have them do a human timeline…

12. Skin Structure

13. Skin Structure Guiding ?’s:
What are the three major layers of the skin?
Describe the basic characteristics of the three major layers of the skin (recommend a chart)

14. Skin: Structure – 3 layers
1. Epidermis: Epithelial
Superficial & thinnest
cells are very tightly packed
New cells produced here
2. Dermis: Connective
Deep to epidermis & thick
Primarily connective tissue
loosely packed cells
3. Subcutaneous/Hypodermis (adipose tissue)
Deep to the skin/dermis
Layer of insulation

15. Diagrammatic vs. Histological view

16. Epidermis Outermost: Stratum corneum Stratum Granulosum
Dry, dead,
keratin filled (waterproof, tough)
Stratum Granulosum
Waterproof
Contains granules of keratin
Stratum Spinosum
“Prickly” layer
Contains Langerhans cells (fight infections)

17. Stratum germinativum / basale
Cells undergoing mitosis, move up and horizontally
Contains malpighian layer or “Pigment layer” with melanosomes
Forms epidermal ridges

19. Stratum corneum:
Dead squamous cells
Stratum lucidum: (only in thick skin); oils from lysosome disintegration
Stratum granulosum:
Granules with lipids and keratin – forms waterproof layer
Stratum Spinosum:
cuboidal cells, desmosomes
hold together >> spiny
Stratum Germinativum/ Basale: dividing columnar cells

20. Epidermis Specialized cells within epidermis: Melanocytes
Melanin: pigment, inc. w/sun (protection)
Keratinocytes
Keratin: tough, waterproof material
Abrasion resistance for cells
Langerhans cells
Immune response against microbes invading the skin

21. Second layer of the skin
Dermis
Second layer of the skin

22. Dermis
Collagen, elastin fibers– scattered

23. Dermal Connective tissue
Dense, irregular connective tissue
Loose, connective tissue = areolar connective tissue
Binds blood vessels, membranes, muscles, nerves, and skin to other structures
Contains extensive meshwork of protein fibers (fibroblasts)
Involved primarily in body growth
Connective tissue maintenance
Wound healing

24. Dermal-epidermal junction
Dermal papillae: parallel rows of
peg-like projections
Unique to each individual; akin to
fingerprints

25. Subcutaneous Layer
Third layer of the skin

26. Subcutaneous layer Third, innermost layer of the skin
Thickness, composition vary throughout body
Composed of loosely-arranged elastic fibers that anchor the skin to the fascia
Sheet of fibrous connective tissue
Covers muscles, skull bones, some organs
Large amount of adipose (fat) cells
Large network of blood vessels, capillaries, lymphatic vessels

27. Skin Appendages
Glands
Nerves
Nails
Hair

28. Glands
3 Types:
Ceruminous
Sebaceous
Sweat/sudoriferous

29. Ceruminous
Produce cerumen (waxy secretion), an apocrine secretion (ear wax)
Found lining ear canal

30. Sebaceous Holocrine glands (secrete whole dead cells)
Produce, store abundance of fat, which burst and die, releasing sebum

31. Specialized Structures of the Dermis
Sebaceous Glands
Secrete oil (sebum) for hair/skin
Ducts open into hair follicles
Accumulated sebum enlarges ducts>>white heads
Darkened sebum>>black head

32. Specialized Structures of Dermis
Sudoriferous/Sweat Glands
Eccrine Glands
Widespread
Watery Fluid
Separate pore
Apocrine Glands
Armpits/Genitals
Thick/milky fluid
Secrete into hair follicle

33. Sweat Aprocrine Eccrine
Odorous, sweat-like material in armpits, navel, groin region, areolae
Inactive until puberty
Contain pheromones
Broken down by bacteria, creating odor
Eccrine
Skin of armpits, foreheads, palms, soles
Mostly secrete water, w/ salts, organic compounds, and wastes (like urea)
Microbes feed on these as well, producing odors

35. Dermis Specialized structures:
Hair follicle: cells of the epidermis extend into the dermis forming a small tube
Hair bulb: base of the follicle
Hair papilla: cluster of cells (live); nourished by BV’s
Root: part of hair hidden in follicle
Shaft: visible part of hair

36. Nerves Sensory receptors Free nerve endings/Nociceptor
Communicate information from environment to the body
Found in all skin layers
Mostly in innermost regions, fascia
Free nerve endings/Nociceptor
Pain-sensing structures
Found throughout inner part of epidermis
Detect chemicals associated with tissue damage and bleeding

38. Encapsulated receptors
Merkel cells
Sensitive to gentle physical sensation
Found in stratum germinativum
Abundant in fingertips

39. Meissner’s (tactile) corpuscles
Elongated, club-shaped pile of connective tissue
Upper region of dermis (in dermal papilla)
Respond to touch

40. Pacinian (lamellated) corpuscle
Look like onions
Deeper parts of hypodermis
Hard pressure, vibrations

41. Ruffini receptors
Pressure, constant touch

42. Krause end bulbs Sensitive touch receptors
Found mostly in mucous membrane of mouth

44. Nails Merely a keratin secretion Nail root Lies beneath skin-nail fold
Grow back as long as nail root and skin-nail fold are not severely damaged
Grow 1/8 in per month

45. Hair Modified stratum corneum
Grows from an individual follicle buried in subcutaneous layer

48. Dermis Specialized Structures (continued)
Arrector pili: tiny, smooth muscle attached to base of dermal papillae & side of hair follicle
Contracts: pulls on both simultaneously>>goose bumps

50. Functions of the Integumentary System

51. Guiding Questions
What are the major roles of the integumentary system?
What are “commensals”?
How does heat regulation in the skin work?
How does sensation in the skin work?
Briefly describe the three classifications of burns

52. Roles of the Integumentary System
Protection
Heat regulation
Sensation
Waste excretion

53. Protection The skin protects from: Chemical Damage
Can break down connections between cells
Can disintegrate cells
Sweat dilutes & neutralizes
Cerumen and sebum are oily barriers
Repels water
Repels dangerous chemicals that are dissolved in water
Prevents water from escaping the body through the skin.

54. Protection The skin protects from: Mechanical Damage
Any type of force that can compress, erode, stretch or tear the skin.
Loose connective tissue = flexibility
Shedding stratum corneum = reduce erosion
Calluses, adipose tissue and reticular fibers = shock absorption to minimize compression damage

55. Protection The skin protects from Microorganism damage
Produce destructive secretions in sebum / sweat
Kept in check by chemicals that benefit commensals— ”good” bacteria and yeast that reduce the chance that harmful bacteria will survive on the skin.
Shedding of stratum corneum removes microorganisms

56. Heat Regulation
The body’s ability to maintain a constant internal temperature (98.6F)
Blood vessels contract / expand
Evaporation of the sweat from the surface
Adipose tissue is a natural “blanket”

57. Sensation
Sensation: received stimuli from the environment which is interpreted in a way that the brain can comprehend
Done by sensory nerves in the skin
Cold, heat, injury, pressure, stretching, touch
Transducers: nerve cells that convert various environmental messages into body signals.

58. Waste Excretion & More Eccrine sweat glands Other functions
Removes urea, organic chemicals, and excess salts
Not as efficient as the Excretory System
Other functions
Vitamin D production when exposed to sunlight
Predictor of a person’s health

59. Burns
Skin loses ability to maintain homeostasis locally and for the whole body
Sun, cooking, acids, bases, corrosive chemicals, electricity, fires, and steam rooms
Damage the skin differently
Severity of burn is based on the extent of the skin damage.

60. First Degree Burns
Reddening, swelling
Superficial damage
Steam, sun

61. First Degree Burn

62. Second Degree Burns Damage to Strata spinosum & basale
Blisters, reddening, swelling and fluid build up under the epidermis

63. Second Degree Burn

64. Third Degree Burns
Entire epidermis affected, could be missing so stratum basale not available
Damage to dermis: nerve cell loss
Pain registers b/c histamine from immune system is released in response to the damage.
Susceptible to dehydration, loss of body heat, and infection

65. Third Degree Burn

66. 4th degree?
Skin entirely damaged; bone, muscle underlying skin damaged as well.
(Too graphic to show)

67. Pathology of the Integumentary System
Guiding Questions:
What are the three major categories of disease in the integumentary system?
What are the various types of degenerative skin disorders? Genetic skin disorders? Infectious skin disorders?

68. Disorders Degenerative Genetic Infectious
Progressive deterioration of tissue, environmental or physical stress
Genetic
Mutations
Infectious
Microorganisms that damage tissues and organs

69. Degenerative Skin Disorders
Solar lentigene
People in their 30s w/ overexposure
Dermatitis
Cosmetics
Facial cleansers
Toners
Can accelerate skin aging

70. Degenerative Skin Disorders
Skin Cancer
Underlying genetic component—precancerous genes
If damaged, genes cause abnormal divisions of cells
Sun exposure
Irregularly shaped black or brown spots that can develop into open sores
Injury deep in the skin
Discolored blisters or sores

72. Degenerative Skin Disorders
Moles: flat squamous cell tumors
Skin tags: soft knobby tumors that grow out of skin
Seborrheic keratosis: Black to brown growth on face or body that creates a greasy, rough appearance to the skin
Sebaceous hyperplasia: caused by oil glands, small yellow bumps with an opening in the middle
Syringomas: sweat-gland duct tumor, small lumps on the cheeks and eyelids
Lipomas: fat cell tumor, don’t cause problems normally

74. Genetic Skin Disorders
Acne: stimulated by hormonal changes that cause and increase in sebum around the hair follicles.
Furuncle or boil: a buildup of dead cells and blood components caused by the inflammation of hair follicles.
Cysts or nodules: a sack-like structure filled with a fluid or semi-solid
Bacteria that feed on the acne pimple produce chemicals that aggravate acne

75. Genetic Skin Disorders
Psoriasis
Increased amt of skin cell production
Causes a build up of thick scales on skin.
Unsightly, inflamed, painful, swollen
Birthmarks
Port wine: begins at birth and grows, can bleed
Spider veins: central blood vessel with smaller vessels branching from it
Strawberry hemangiomas: enlarged blood vessels

76. Genetic Skin Disorders
Vitiligo
Michael Jackson
White spots—hypopigmentation
Reduced melanocytes
Albinism
No melanin production in the eyes, hair or skin
Melasma
Brown patches on both sides of the face
Symmetrical
Does not completely disappear

77. Infectious Skin Disorders
Staphylococcus aureus (bacteria)
destructive secretions that erodes and inflame the skin
Impetigo, SSSS, folliculitis
Candida albicans (fungus)
Yeast in digestive system and female reproductive tract infect skin when immune system is compromised
Degrade tissue and cause inflammation

78. Infectious Skin Disorders
More fungal infections = dermatophytes
Eat keratin-rich materials: hair, nails, and outer layers of epidermis
Itching, hair loss, deformation of nails
Ringworm (aka tinea)
Contracted from furry pets
Spread from one person to another through contact via clothes and skin
Related to athlete’s foot or jock itch

79. Infectious Skin Disorders
Warts (virus)
60 types
HPV (human papilloma virus)
Incurable
Removal procedure
Protists
Exotic tropical diseases that are spread by insect bites.
Can cause severe bodily damage if spread to internal organs

80. Infectious Skin Disorders
Arthropods
Insects with exoskeletons, segmented bodies, jointed limbs
Follicle mite—undetected until inflammation of eyelash follicle occurs
Lice—blood sucking insects that irritate skin and spread infection as they feed

81. Aging of the Integumentary System
Guiding Questions
What are “intrinsic” factors? How can they affect the skin’s aging?
What kinds of extrinsic factors can affect skin aging?
How does lifestyle accelerate skin aging?

82. Aging Extrinsic Intrinsic Also external aging
Environmental factors: disease, pollution, sun
Intrinsic
Natural maturation
Also internal aging
Accelerated by stress—pathology of other organ systems or environmental interactions

83. Aging Characteristics of skin aging Loss of head hair
Graying and whitening of hair
Excessive growth of body and facial hair
Wrinkling
Drying of the skin due to diminished oil secretion
Skin sagging due to muscle atrophy
Regular irritation due to microbial population changes on the skin

84. Aging Impossible to stop Natural decline of cells
Can be slowed by living in a mild environment
Elastin is naturally degraded by the dermis and subcutaneous layers
Makes the skin less flexible, thinner, more brittle
Decrease in blood flow slows cell division in basale & causes thinning of the epidermis
More difficult to repair skin damage
People with vascular diseases exhibit premature aging

85. Aging Decrease in melanocytes, nerves Susceptible to DNA damage
More susceptible to environmental damage
Older skin can’t protect from UV and has difficulty registering injury.
Susceptible to DNA damage
Oxidizing chemicals and sunlight
Cause cancers and tumors

86. Aging
How to slow…
Diet, reducing exposure to UV, avoiding skin irritation, not smoking, protecting from air pollutants
Smoking reduces blood flow to skin
Can’t heal
Decreases ability to maintain body’s temp
Skin needling
Promotes growth and swelling in wrinkled depression areas
Makes skin smooth for a while
Take care of skin at a young age…difficult to reverse skin aging once the damage is done