10/23/2015 1 The Integumentary System The Integumentary System Integument is skin Skin and its appendages make up the integumentary system A fatty layer (hypodermis) lies deep to it Three distinct regions Epidermis Dermis Hypodermis Functions of skin Protection Cushions and insulates and is waterproof Protects from chemicals, heat, cold, bacteria Screens UV Synthesizes vitamin D with UV Regulates body heat Prevents unnecessary water loss Sensory reception (nerve endings)
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10/23/2015
1
The Integumentary System
The Integumentary System
Integument is skin
Skin and its appendages make up the integumentary system
A fatty layer (hypodermis) lies deep to it
Three distinct regionsEpidermis
Dermis
Hypodermis
Functions of skin
Protection Cushions and insulates and is waterproof
Protects from chemicals, heat, cold, bacteria
Screens UV
Synthesizes vitamin D with UV
Regulates body heat
Prevents unnecessary water loss
Sensory reception (nerve endings)
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Epidermis
Keratinized stratified squamous epithelium Four types of cellsKeratinocytes – deepest, produce keratin
(tough fibrous protein)Melanocytes - make dark skin pigment
melanin Merkel cells – associated with sensory
nerve endings Langerhans cells – macrophage-like
dendritic cells
Epidermis
Layers (from deep to superficial)Stratum basale or germinativum – single row of
cells attached to dermis; youngest cellsStratum spinosum – spinyness is artifactual;
tonofilaments (bundles of protein) resist tensionStratum granulosum – layers of flattened
keratinocytes producing keratin (hair and nails made of it also)
Stratum lucidum (only on palms and soles)Stratum corneum – horny layer (cells dead,
many layers thick)
(see figure on next slide)
Epithelium: layers (on left) and cell types (on right)
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Remember…
Four basic types of tissue
Epithelium – epidermis just discussed
Connective tissue - dermis
Muscle tissue
Nervous tissue
Dermis
Strong, flexible connective tissue: your “hide” Cells: fibroblasts, macrophages, White Blood
Cells Fiber types: collagen, elastic, reticular Rich supply of nerves and vessels Critical role in temperature regulation (the
vessels) Two layers (see next slides)
Papillary – areolar connective tissue; includes dermal papillae
Reticular – “reticulum” (network) of collagen and reticular fibers
*Dermis layers
*
*
*Dermal papillae
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Epidermis and dermis of (a) thick skin and (b) thin skin(which one makes the difference?)
Fingerprints, palmprints, footprints Dermal papillae lie atop dermal ridges
Made of areolar tissue
Elevate the overlying epidermis into epidermal ridges Are “sweat films” because of sweat pores Genetically determined
Flexion creases Deep dermis, from continual folding
Fibers Collagen: strength and resilience Elastic fibers: stretch-recoil
Striae: stretch marks Tension lines (or lines of cleavage)
The direction the bundlesof fibers are directed
The dermis is the receptive site for the pigment of tattoos
Hypodermis
“Hypodermis” (Gk) = below the skin
“Subcutaneous” (Latin) = below the skin
Fatty tissue which stores fat and anchors skin (Adipose cells)
Different patterns of accumulation
(male/female)
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Skin color
Three skin pigmentsMelanin: the most importantCarotene: from carrots and yellow vegiesHemoglobin: the pink of light skin
Melanin in granules passes from melanocytes (same number in all races) to keratinocytes in stratum basaleDigested by lysosomesVariations in colorProtection from UV light vs vitamin D?
Skin Accessory Structures
Derived from epidermis but extend into dermis
IncludeHair and hair follicles
Sebaceous (oil) glands
Sweat (sudoiferous) glands
Nails
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Nails
Of hard keratin
Corresponds to hooves and claws
Grows from nail matrix
Hair and hair follicles: complexDerived from epidermis and dermisEverywhere but palms, soles, nipples, parts of genitalia
*“arrector pili” is smooth muscle
*
Hair papilla is connective tissue________________
Hair bulb: epithelial cells surrounding papilla
Functions of hairWarmth – less in man than other mammalsSense light touch of the skinProtection - scalp
PartsRoot imbedded in skinShaft projecting above skin surface
Make up of hair – hard keratin Three concentric layersMedulla (core)Cortex (surrounds medulla)Cuticle (single layers, overlapping)
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Types of hair Vellus: fine, short hairs Intermediate hairs Terminal: longer, courser hair
Hair growth: averages 2 mm/week Active: growing Resting phase then shed
Hair loss Thinning – age relatedMale pattern baldness
Hair color Amount of melanin for black or brown; distinct form of
melanin for redWhite: decreased melanin and air bubbles in the
medullaGenetically determined though influenced by
hormones and environment
Sebaceous (oil) glands
Entire body except palms and soles
Produce sebum by holocrine secretion
Oils and lubricates
Sweat glands Entire skin surface
except nipples and part of external genitalia
Prevent overheating 500 cc to 12 l/day!
(is mostly water) Humans most
efficient (only mammals have)
Produced in response to stress as well as heat
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Types of sweat glands Eccrine or merocrine
Most numerous True sweat: 99% water, some salts, traces of wasteOpen through pores
Apocrine Axillary, anal and genital areas only Ducts open into hair follices The organic molecules in it decompose with time - odor
Modified apocrine glands Ceruminous – secrete earwaxMammary – secrete milk
UV Radiation 200 nm 280nm 320nm
400nmUVC UVB UVA
(absorbed by ozone) (highly carcinogenic) (weakly carcinogenic)
Acute & Chronic effects from UV radiation
Short term – itching, nausea, pruritis, xerosisLong term - polymorphous light eruption, disseminated superficial actinic porokeratosis, mid-dermal electrolysis and actinic granulomas, melanomas, basal and
squamous cell carcinomas
Pre-existing photosensitivity in Lupus Erythmatosus, Polymorphous Light Eruption, Porphyria, and Rosacea significantly exacerbated by exposure to indoor tanning
Emergence of tanning
1930’s & 40’s – Medical profession encouraged sun exposure as benefit to children
1948 – First reported studies of vitiligo with oral & topical psoralen
Development of ‘tan’ for cosmetic purposes – French designer Coco Chanel
1970’s – Development of UVA beds for medicinal purposes
Commercialization soon after with formation of the Indoor Tanning Association
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Skin cancers
Melanoma in U.S –
Incidence rates rising by 4-8% each year
Lifetime incidence is 1/71
3% of all cancers
1% of all cancer deaths
Most common cause of death in women 30-39 years
Skin Cancers - Melanomas
Melanoma in the U.S
0
10000
20000
30000
40000
50000
60000
70000
2000 2001 2002 2003 2004 2005 2006
Year
New
cas
es
7000
7200
7400
7600
7800
8000
Dea
ths
New cases Melanoma Deaths
Skin cancers - Melanomas
Risk factors:
Family history Red/Blond hair Ample UV exposure (freckling on upper back, history
of 3 or more sunburns before age 20, 3 or more outdoor jobs before age 20)
Actinic keratosis Skin types I & II Advanced age Atypical or congenital nevi
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Skin typesFitzpatrick’s classification – 1977
SED = sub erythemal dose
Skin type assessment
Sun sensitivity or skin type remains constant during a lifetime
Self assessment by individual tanners
Assessment by low-wage, insufficiently trained tanning salon operators
Indoor Tanning Association
Total Number of Professional Indoor Tanning Facility Businesses: 25,000
Total Number of Professional Tanning Business Employees: 160,000
Total Professional Indoor Tanning Facility Customer Base: 30 million
Total Revenues Professional Indoor Tanning Facilities: $5 billion
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Indoor Tanning Industry
Misleading advertisements &/or falsified messages:
Promoting UV protection through indoor tanning (lack of sufficient epidemiological evidence)
Promotion of health benefits through Vitamin D production
Promotion of trade-offs of certain internal cancers
Stand against sunscreens
Indoor Tanning IndustrySignificant advertising & promotion to students
Formed a Political Action Committee (PAC) to prevent ban on under-18 tanning
Indoor Tanning Industry
Tanning salon operator education:
Through 2 private institutions – National tanning Training Institute (NTTI) and International Smart Tan Network (ISTN).
No training for skin typing
No training for radiation related burns and/or emergency procedures
No demonstration of equipment handling
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Indoor Tanning
Source: www.cartoonstock.com
Tanning Salon Operators
Source: www.cartoonstock.com
Regulation & Legislation
FDA – regulates equipment, adherence to performance standards, warning signs (FDA, 21 CFR Ch.1 § 1040.20)
Regulation since 1979 – Federal standards adopted to protect customers from eye and skin injuries
1985 – Amendments by allowing longer exposure times for UVA emitting lamps
1986 – Policy letter published on recommended exposure schedules
Currently – no regulation or monitoring of exposure times of patrons, no requirements for maintaining much information
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Regulation & Legislation
FTC – prohibits deceptive advertising
Individual states governance
Screening
Differences of opinions:
AAD, ACPM – regular screeningIOM, NCI – insufficient evidence for screeningUSPSTF, CTF – screening at-risk population
Early detection of melanomas: High 5-year survival rate
External & visible cancer with known risk factors
Discussion
According to Sharon A. Miller at the FDA’s Center for Devices and radiological Health:
“FDA does not recommend the use of indoor tanning equipment”
Comments:- FDA does not regulate prevalence of indoor
tanning- Currently no legislation protecting minors explicitly- No safeguards in place to protect the general
tanning population - No requirements for exposure schedules or
monitoring of UV radiation sessions in tanning salons
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Disorders of the integumentary system
BurnsThreat to life
Catastrophic loss of body fluids Dehydration and fatal circulatory shock Infection
Types First degree – epidermis: redness (e.g. sunburn) Second degree – epidermis and upper dermis: blister Third degree - full thickness
Infections Skin cancer
BurnsFirst-degree(epidermis only; redness)
Second-degree(epidermis and dermis,with blistering)
Third-degree(full thickness, destroying epidermis, dermis, often part of hypodermis)
Critical burns
Over 10% of the body has third-degree burns
25 % of the body has second-degree burns
Third-degree burns on face, hands, or feet
Estimate by “rule of 9’s”
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Tumors of the skin
Benign, e.g. warts Cancer – associated with UV exposure
(also skin aging)Aktinic keratosis - premalignantBasal cell - cells of stratum basaleSquamous cell - keratinocytesMelanoma – melanocytes: most dangerous;
recognition: A - Asymmetry B - Border irregularity C - Colors D - Diameter larger than 6 mm
Basal cell carcinoma
Sqaumous cell carcinoma
Melanoma
Skin Cancer
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