1. 5
The Integumentary System

2. An Introduction to the Integumentary System
Integument is the largest system of the body
Dermatology: study of integumentary system and associated pathologies

3. Integumentary System: Overall Structure
Cutaneous membrane or skin
Epidermis
Dermis
Hypodermis-not technically part of skin
Accessory structures
Hair
Nails
Sweat Glands (Sudoriferous glands)
Sebaceous Glands (Oil glands)

4. Cutaneous Membrane (Skin)
Epidermis
Superficial epithelium
Dermis
Deeper connective tissue
Papillary Layer
Reticular layer

5. Components of the Integumentary System
Accessory Structures
Cutaneous Membrane
Epidermis
Hair shaft
Pore of sweat gland duct
Papillary layer
Dermis
Tactile corpuscle
Reticular layer
Sebaceous gland
Arrector pili muscle
Sweat gland duct
Hair follicle
Hypodermis
Lamellated corpuscle
Nerve fibers
Sweat gland
Artery
Cutaneous plexus
Vein
Fat 5

6. Functions of the skin Protection
Stratified epidermis…protects from abrasions
Keratin…water proofing
Melanin…protects from UV
WBC in dermis…immunity
Temperature regulation
Sweat…evaporates to cause cooling
Blood vessels…vasoconstriction/vasodilation to regulate heat loss from warm blood in the skin
Arrector pili…goose bumps

7. Functions of the skin Sensation
Nerves to sense touch, temperature and injury (pain)
Excretion
Sweat…salts, organic substances
Synthesis of vitamin D
For absorption of calcium

8. The Epidermis
Is an avascular, keratinized stratified squamous epithelium
Nutrients and oxygen diffuse from capillaries in the dermis
Top layer of dead cells: thickness varies with body location

9. Five Principle Cells of the Epidermis
Keratinocytes:
Most abundant skin cell, forms several strata
Produces keratin, helps protect the from heat, microbes, and chemicals, and releases a waterproof sealant
Melanocytes
Melanin production-contributes to skin color and absorbs damaging ultraviolet (UV) light
Langerhans (Dendritic) cells
Derived from bone marrow, participate in immune response
Merkel cells
Contact a tactile (Merkel) disc and function in the sensation of touch
Stem cells
Undergo mitosis to produce new keratinocytes

10. Types of Cells found in the epidermis

11. Stratum lucidum (Thick skin only) Stratum corneum
Epidermis
Consists of four (thin skin) or five (thick skin) layers or strata
From basal lamina to free surface
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum (Thick skin only)
Stratum corneum
BSGLC (Buy Some Gum Leave a Crumb!)

12. Figure 5-2 The Basic Organization of the Epidermis
Stratum corneum
Epidermis
Stratum lucidum
Epidermal ridge
Basement
membrane
Dermal papilla
Dermal papilla
Dermis
Dermis
Epidermal ridge
Thin skin
LM  154
Thick skin
LM  154
The structural relationship and interface between the epidermis and underlying dermis. The proportions of the various layers differ with the location sampled.
A micrograph of thin skin, which covers most of the exposed body surface.
A micrograph of thick skin, which covers the surface of the palms and the soles of the feet. 12

13. Thin Skin
Skin is thin and smooth
Most regions of the body
Epidermis has four layers:
S corneum
S granulosum
S spinosum
S basale
S corneum is thinner
Sebaceous glands are present
Fewer sudoriferous glands
Fewer sensory receptors
Thick Skin
Skin is thicker and rougher
Specific regions – palm and sole
Epidermis has five layers:
S corneum
S lucidum
S granulosum
S spinosum
S basale
S corneum is thicker
Sebaceous glands are absent
More sudoriferous glands
More sensory receptors

14. Figure 5-3 The Structure of the Epidermis
Surface
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
Basement membrane
Papillary layer of dermis
Dermis
Thick skin
LM  210 14

15. Stratum basale
Deepest layer
Single layer of cells resting on basement membrane
Epidermal ridges extend into dermis
Contains Stem cells-Produce new cells that are pushed upwards
Also contains melanocytes (make melanin) and Merkel cells (touch sensation)

16. Melanocytes in stratum basale
Figure 5-5 Melanocytes
Melanocytes in stratum basale
Melanin pigment
Basement membrane
Melanocytes
LM  600
Melanosome
Keratinocyte
Melanin pigment
Melanocyte
Basement membrane 16

17. Stratum spinosum
8-10 layers of keratinocytes
Phagocytize melanin from melanocytes present in S. basale layer
Contain dendritic (Langerhans) cells, active in immune response
Stratum granulosum
3-5 layers of non-dividing keratinocytes
Keratinocytes making keratin
Degenerating nucleus…dying cells

18. Stratum lucidum:
Dying keratinocytes, largely devoid of organelles, filled with keratin
Present only in thick skin (palm, sole)
Stratum corneum:
Top protective barrier layer
15 to 30 layers of dead keratinized cells
Packed with keratin
Water resistant
Continuously shed (~ 2 weeks)

19. ~ 7-10 days for passage of cell from S.basale to S. corneum
Keratinization is the formation of a layer of dead, protective cells filled with keratin
Occurs on all exposed skin surfaces except eyes
Dead cells remain in stratum corneum layer for ~ 2 weeks
Cells connected by desmosomes

20. Dehydration Stratum corneum is water resistant but not waterproof
Insensible perspiration: Constant loss of water from interstitial fluids by evaporation into air (~500 ml/day)
Sensible perspiration: Water loss through active sweat glands
Water loss is inhibited by stratum corneum
Water loss can be accelerated by:
damage to stratum corneum (e.g., burns and blisters)
immersion in hypertonic solution (e.g., seawater [osmosis])

21. 5-5 The Dermis
Located between epidermis and hypodermis (subcutaneous layer)
Contains
hair follicles
glands
nerves
blood vessels
Two components
Outer papillary layer
Areolar connective tissue
Deeper reticular layer
Dense irregular connective tissue

22. The Dermis Epidermis Dermis Hypodermis Papillary layer Reticular layer
Cutaneous Membrane
Epidermis
Dermis
Papillary layer
Reticular layer
Hypodermis

23. 5-5 The Dermis Papillary Layer: Areolar (loose) connective tissue
Upper region of dermis
Contains capillaries, lymphatics and sensory nerves that support the epidermis
Contains Meissner’s corpuscles (touch) & free nerve endings for sensations of heat, cold, pain, tickle, and itch
Has finger like projections - dermal papillae;

24. Dermis: Papillary Layer
Dermal papillae project into epidermis
Reflect on the surface as epidermal ridges and fingerprints
Dermal papillae/epidermal ridges: Functions:
Increase friction for grasping objects
Firmly bind epidermis to dermis
Dermis
Epidermis
Epidermal ridge
Dermal papilla

25. Reticular Layer:
Lower region of dermis
Dense irregular connective tissue
Has glands, hair follicles, fat tissue, blood and lymphatic vessels & nerves
Specific arrangement of collagen fibers reflect on the surface as cleavage lines and wrinkle lines
Causes stretch marks if overstretched: pregnancy, obesity
Provides strength and elasticity to the skin

26. Cleavage Lines of the Skin
Lines of cleavage
Formed by arrangement of collagen and elastin fibers in the skin
Clinically significant for surgery and wound healing
Parallel to cleavage: better healing and less scarring
Perpendicular to cleavage: remain open and more scarring
ANTERIOR
POSTERIOR 26

27. The Hypodermis
Also called Subcutaneous Layer; Superficial fascia
Connects skin to muscle layer
Consists of adipose and areolar connective tissue,
Contains pressure-sensing nerve endings (pacinian corpuscles) and cutaneous plexus (arteries/veins)
Functions as energy reservoir, thermal insulation
The site of subcutaneous injections using hypodermic needles

28. 5-2 Skin Color Three main factors affecting skin color 1. Melanin
Yellow-brown or black pigment manufactured from tyrosine
Made by melanocytes in S basale layer-stored & trasported in melanosomes
Pigment phagocytized by keratinocytes of upper layers of epidermis
Amount of pigment is controlled by:
Genetics
UV exposure
Hormone

29. 5-2 Skin Color
2. Carotene
Orange/Yellow pigment (found in yellow fruits and vegetables)
Accumulates in epidermal cells and fatty tissues of the dermis
Gives yellow hue to the skin
Used to make vitamin A: required for maintenance of epithelia and for the synthesis of photoreceptors of the eye
3. Hemoglobin-Blood vessels
Network of capillaries varies in dermis
Gives reddish color to the skin

30. Skin Color-Diagnostics
Jaundice - yellowish color to skin and whites of eyes. Liver unable to excrete bile, buildup of yellow bilirubin in blood from liver/blood disease
Cyanosis - bluish color in the nails and skin due to severe reduction in blood flow or oxygenation-for e.g severe cold, heart failure
Erythema: redness of skin due to dilation of blood capillaries in the dermis, caused by inflammation, infection, allergy, burns, anger, embarrasment
Pallor (blanching): due to emotional stress such as fear, anemia, low blood pressure, impaired blood flow to an area

31. Skin Color-Diagnostics
Albinism: melanocytes are present but melanin gene is mutated  little or no melanin made  no color in the skin, hair and eyes
Vitiligo: partial or complete loss of melanocytes  patchy skin, thought to be autoimmune disorder
Pituitary tumor: Produce excess Melanocyte Stimulating Hormone (MSH)-Skin darkening
Addison’s disease: A disease of the pituitary gland resulting in increased secretion of adrenocorticotropic hormone (ACTH) which is structurally similar to MSH-skin darkening

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5-7 Hair and other accessory structures
Located primarily in dermis but of epidermal origin
Hair & Hair Follicles
Nails
Sebaceous Glands
Sweat Glands

33. 5-7 Hair
Hairs are mostly non-living structures produced in organs called hair follicles
strands of dead cells filled with keratin
Terminal hair-large, coarse, more darkly pigmentted-eg scalp hair
Vellus hair-finer, shorter-most of body surface
Hair functions
Protects against UV
Insulation
Guards openings (eye, ear, nostrils) against particles and insects
Sensory receptors-sensitive to very light touch

34. 5-7 Hair
Hair parts:
Shaft: upper part, extends above skin surface, dead epithelial cells
Root: embedded in skin, anchors hair, dead epithelial cells
Hair bulb: swollen mass of living epithelial cells at base of the hair follicle
Hair papilla
Small amount of connective tissue projecting into hair bulb
Contains blood vessels to provide nutrients, and also nerves
Hair matrix
Superficial cells of the hair bulb
Growth center of hair: Contains actively dividing basal cells
Hair shaft
Sebaceous gland
Arrector pili muscle
Hair root
Connective tissue sheath
Hair bulb
Hair matrix
Hair papilla

35. Accessory Structures of Hair
Arrector pili muscle
Involuntary smooth muscle
When stimulated, contracts and
causes hairs to stand up
Produces “goose bumps”
Sebaceous (oil) glands
Lubricate the hair
Control bacterial growth
Exposed shaft of hair
Sebaceous gland
Arrector pili muscle
Connective tissue sheath
Root hair plexus

36. Hair Color
Depends upon amount and type of melanin:
Dark hair – a lot of melanin
Gray hair – decrease in melanin production
White hair – absence of melanin and presence of air bubbles in hair medulla

37. 5-9 Nails Protect fingers and toes
Made of dead cells packed with keratin
Metabolic disorders can change nail structure

38. Nail body: Visible part, tightly packed dead cells that are filled with keratin
Nail root: epidermal part embedded into the skin, where nail production occurs
Nail bed: epidermis underlying nail body
Lunula: white region of the nail body…thickened stratum basale obscures underlying blood vessels
Eponychium (cuticle): a portion of epidermis (stratum corneum) that projects over the nail body
Nail growth: in the nail matrix surrounding the nail root

39. 5-8 Sebaceous Glands and Sweat Glands
Exocrine Glands in Skin
Sebaceous Glands (oil glands)
Secrete sebum
Sweat Glands(sudoriferous glands)
Watery secretions

40. Associated with hair follicles Holocrine secretion
Sebaceous glands
Associated with hair follicles
Holocrine secretion
Secrete sebum-lipids, proteins, fats & salts
Stimulated by sex hormones during puberty
Functions
Antimicrobial
Lubrication & protection of the skin and hair
Sebaceous follicles
Larger glands
Discharge directly onto skin surface
Sebaceous
gland
Sebaceous follicle
Epidermis
Dermis
Subcutaneous layer

41. Sudoriferous Glands
Widely distributed on body surface, especially on palms and soles
Coiled, tubular glands that discharge secretions directly onto skin surface
Sensible perspiration
Watery secretions-Sweat (99% Water, electrolytes (NaCl), antimicrobial peptide, organic nutrients & wastes) is discharged directly onto skin surface
Functions
Thermoregulation
Excretion of salts and wastes
Protection-flushing action
Duct of merocrine sweat gland

42. Other Integumentary Glands
Mammary glands
Produce milk
Ceruminous glands
Found in ear canal
Produce cerumen (earwax)
Protect the eardrum

43. 5-10 Repair of the Integument
Epidermis is damaged. Stratum basale cells from the periphery of the wound --> migrate towards the center --> cells divide to form new epithelial cells to replace the loss tissue --> skin epidermis becomes normal
Superficial Wound

44. What are the steps involved in Deep Wound Healing?
Bleeding occurs at the site of injury immediately after the injury, and mast cells in the region trigger an inflammatory response.
Epidermis
Dermis
Mast cells 44

45. Figure 5-14 Repair of Injury to the Integument
After several hours, a blood clot (scab) has formed
and cells of the stratum basale are migrating along the edges of the wound. Phagocytic cells are removing debris, and more of these cells are arriving via the enhanced circulation in the area. Clotting around the edges of the affected area partially isolates the region.
Migrating epithelial cells
Macrophages and fibroblasts
Granulation tissue
Granulation tissue: consists of blood clot, fibroblasts, and extensive capillary network which will become covered with epithelial tissue 45

46. Figure 5-14 Repair of Injury to the Integument
One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblast activity. Phagocytic activity around the site has almost ended, and the fibrin clot is breaking up.
Fibroblasts 46

47. Figure 5-14 Repair of Injury to the Integument
After several weeks, the scab has been shed, and the epidermis is complete. A shallow depression marks the injury site, but fibroblasts in the dermis continue to create scar tissue that will gradually elevate the overlying epidermis.
Scar tissue
Fibroblasts produce scar tissue (lots of collagen fibers) which completes the repair process but does not restore the tissue to its original condition 47

48. Figure A Keloid
In some adults, scar tissue formation may continue beyond tissue repair-A raised keloid may form 48

49. 1. Sunlight. Limited exposure to UV is beneficial
5-3 Vitamin D3: Sources
1. Sunlight. Limited exposure to UV is beneficial
Epidermal cells produce vitamin D3 (Cholecalciferol) in the presence of UV radiation
Liver creates intermediate product then converted to calcitriol by kidneys
Calcitriol aids absorption of calcium and phosphorus needed for bone maintenance and growth
2. Diet.
Naturally from fish, fish oils, and shellfish
From fortified food products

50. Vitamin D3 Insufficient vitamin D can cause rickets in children
Condition resulting in weak, poorly mineralized, flexible bones
Bend under body weight
Uncommon in United States
In elderly, skin production of
cholecalciferol decreases by 75%

51. Skin Cancer 3 common forms of skin cancer
Basal cell carcinoma: rarely metastasizes, most common, originates in stratum basale.
Squamous cell carcinoma: may metastasize, originate in stratum spinosum
Malignant melanomas: metastasizes rapidly
most common cancer in young women, life threatening
arise from melanocytes
key to treatment is early detection
risks factors include-- skin color, sun exposure, family history, age and immunological status

52. Skin Cancer
Figure 5.11

53. Know the ABCD for early melanoma detection
Figure 5-6 Skin Cancers
Prevention: Avoid excessive sun exposure, sunblocks prevent against sunburn
Know the ABCD for early melanoma detection
Asymmetry-one side different from the other, typically raised
Border-irregular
Color –combinations-often mixture brown, black & tan
Diameter (> 5 mm/0.2 inch) 53

54. Skin burns Caused by: Fire, electricity, radiations, and chemicals
Effects on the body:
Dehydration
Lowered body temperature
Decreased blood pressure
Decreased or no urine production (kidneys shut down)
Infections

55. Severity of Burns First-degree burns Only upper epidermis is damaged
Most sunburns
Pain, Skin is red (erythema) and swollen, flaking & peeling
Second-degree burns
Epidermis and usually upper dermis are damaged
Pain, Skin is red (erythema) with blisters

56. Severity of Burns Third-degree burns (Full thickness)
Destroys the epidermis & dermis & accessory structures); may extend to hypodermis
Less painful due to destroyed sensory nerves
Extensive burns cannot repair and requires skin graft

58. Symptoms and Treatment
A third degree (full-thickness) burn injury can be life threatening if it covers >20% of body surface.
Symptoms and Treatment
Fluid and electrolyte loss-Ivs to replace
Increased evaporative cooling-High-calorie diet
Infection prone-Antibiotics, Aseptic environment, debridement, high calorie diet
Skin grafts

59. Effects of Aging on the Integumentary System
Fewer Melanocytes
Fewer Active Follicles
Reduced Skin Repair
Decreased Immunity
• Pale skin
The number of dendritic cells decreases to about 50 percent of levels seen at maturity (roughly age 21).
• Reduced tolerance for sun exposure
Skin repairs proceed more slowly.
Thinner, sparse hairs
Thin Epidermis
• Slow repairs
• Decreased vitamin D production
• Reduced number of Langerhans cells
Reduced Sweat Gland Activity
Tendency to overheat
Changes in Distribution of Fat and Hair
Dry Epidermis
Reduced Blood Supply
Thin Dermis
Reduction in sebaceous and sweat gland activity
• Slow healing
Sagging and wrinkling due to fiber loss
Due to reductions in sex hormone levels
• Reduced ability to lose heat 59

60. 5-11 Importance of the Integumentary System
Protects and interacts with all organ systems
For example:
Cardiovascular system: Blood vessels in the dermis
Nervous system: Sensory receptors for pain, touch, and temperature
Changes in skin appearance are used to diagnose disorders in other systems

61. Integumentary System-Clinical
Acne: Inflammation of the sebaceous glands, blocked follicles, onset at puberty
Dermatitis: Inflammation of the papillary layer of the dermis, Caused by infection, radiation, mechanical irritation, or chemicals (e.g., poison ivy), Characterized by itch or pain
Eczema: Allergic inflammation of the skin, onset usually in early childhood
Ulcer: Localized shedding of epithelium
Liposuction/Lipoplasty: Surgical removal of adipose tissue from the subcutaneous layer.