Skin: The Integumentary System

Skin:Skin:

The Integumentary SystemThe Integumentary System

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FunctionsFunctions

Provides a barrier against hazardous materials Provides a barrier against hazardous materials and pathogensand pathogens

Major receptor for the sense of touchMajor receptor for the sense of touch

Waterproofs the body and prevents fluid lossWaterproofs the body and prevents fluid loss

Helps the body synthesize vitamin D from Helps the body synthesize vitamin D from ultraviolet lightultraviolet light

IntegumentIntegument means “covering” means “covering”

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StructuresStructures

SkinSkin– Largest organ of the bodyLargest organ of the body– Approx 5 kg in the average humanApprox 5 kg in the average human– Dermat/o, cutane/oDermat/o, cutane/o mean skin mean skin

– Made up of two distinct tissue layers and an Made up of two distinct tissue layers and an underlying layer of fatty tissueunderlying layer of fatty tissue

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Skin LayersSkin Layers

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– EpidermisEpidermisOutermost layer of skinOutermost layer of skin

Consists of stratified squamous epitheliumConsists of stratified squamous epithelium

Top layers are flat overlapping cells that contain Top layers are flat overlapping cells that contain soft soft keratinkeratin (fibrous, water-repellant protein) – (fibrous, water-repellant protein) – form the waterproof barrierform the waterproof barrier

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Lower layer is the Lower layer is the basal layerbasal layer – produces the – produces the epithelial cells that get pushed toward the surface epithelial cells that get pushed toward the surface where they die and become filled with where they die and become filled with keratinkeratin

The dead cells slough off so new cells can The dead cells slough off so new cells can take their placetake their place

The basal layer also contains The basal layer also contains melanocytesmelanocytes that that produce produce melaninmelanin (the dark brown pigment that (the dark brown pigment that determines skin colour, produces freckles, and determines skin colour, produces freckles, and protects against ultraviolet light)protects against ultraviolet light)

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– DermisDermisAKA coriumAKA coriumContains connective tissue, blood and lymph Contains connective tissue, blood and lymph vessels, nerve fibersvessels, nerve fibers

– CollagenCollagen – tough, flexible, fibrous protein– tough, flexible, fibrous protein– Mast CellsMast Cells – respond to injury, infection, or – respond to injury, infection, or

allergy by releasing substances like histamine allergy by releasing substances like histamine and heparinand heparin

Provides a living substrate for the epidermis, and Provides a living substrate for the epidermis, and contains the accessory structures, such as hair contains the accessory structures, such as hair follicles, glands, and nerve endingsfollicles, glands, and nerve endings

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– Subcutaneous LayerSubcutaneous LayerConnects the skin loosely to the underlying Connects the skin loosely to the underlying musclesmuscles

Consists of loose connective tissue and adipose Consists of loose connective tissue and adipose tissuetissue

– SubcutaneousSubcutaneous means “below the skin” means “below the skin”

Provides a cushion against shock, and insulation Provides a cushion against shock, and insulation against temperature changesagainst temperature changes

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Accessory StructuresAccessory Structures

Sebaceous GlandsSebaceous Glands– Associated with hair folliclesAssociated with hair follicles

Except on palms of Except on palms of hands and soles of feet hands and soles of feet (most concentrated in the (most concentrated in the scalp)scalp)

– Secrete Secrete sebumsebum – an oily – an oily substance which lubricates substance which lubricates the skin and discourages the skin and discourages bacterial growth (it is slightly bacterial growth (it is slightly acidic)acidic)

Also helps to prevent Also helps to prevent water losswater loss

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Sweat GlandsSweat Glands– AKA sudoriferous glandsAKA sudoriferous glands– Tiny, coiled glands that secrete Tiny, coiled glands that secrete perspiration perspiration (sweat) (sweat)

to the body surfaceto the body surface

Most numerous on the palms of the hands, soles of Most numerous on the palms of the hands, soles of the feet, forehead, armpitsthe feet, forehead, armpits

Perspiration is composed primarily of water and Perspiration is composed primarily of water and some salt and waste productssome salt and waste products

Functions to excrete excess water and cool the Functions to excrete excess water and cool the bodybody

Hidr/oHidr/o means sweat means sweat– HidrosisHidrosis is the production of sweat is the production of sweat

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– Eccrine Sweat glandsEccrine Sweat glandsOpen onto the skin surface Open onto the skin surface and secrete through and secrete through openings called openings called porespores

Most numerous typeMost numerous type

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– Apocrine Sweat glandsApocrine Sweat glandsOpen into hair folliclesOpen into hair follicles

Most numerous in armpit and Most numerous in armpit and external genitaliaexternal genitalia

Substance secreted also Substance secreted also contains contains proteins and fatty acids which proteins and fatty acids which give it a yellow colourgive it a yellow colour

Respond to pain, emotional Respond to pain, emotional stress, sexual arousal, etcstress, sexual arousal, etc

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Hair (Hair (trich/o, pil/otrich/o, pil/o))– Columns made of dead protein cells Columns made of dead protein cells

filled with hard keratinfilled with hard keratin– Melanocytes in the follicle produce Melanocytes in the follicle produce

melanin which colours the hairmelanin which colours the hair– Follicle: sac that holds the root of the Follicle: sac that holds the root of the

hair (its shape determines whether hair (its shape determines whether hair will be straight or curly)hair will be straight or curly)

– Arrector pili – tiny muscle fibers that Arrector pili – tiny muscle fibers that contract to make the hair stand erect contract to make the hair stand erect (reduces heat loss through the skin)(reduces heat loss through the skin)

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NailsNails– Thin plates of keratinized cells that protect the end of Thin plates of keratinized cells that protect the end of

the the fingers and toesfingers and toes

– Nail Body: translucent, closely molded to underlying Nail Body: translucent, closely molded to underlying tissuestissues

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– Nail Bed: joins the nail body Nail Bed: joins the nail body to the underlying tissue and nourishes the nailto the underlying tissue and nourishes the nail

Very vascularized – givesVery vascularized – gives the nail its pink colour the nail its pink colour

– Root: fastens the nail to the finger or toe by fitting it Root: fastens the nail to the finger or toe by fitting it into a groove in the skininto a groove in the skin

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Free Edge: portion of the nail body not attached to the Free Edge: portion of the nail body not attached to the nail bed (white portion of the nail)nail bed (white portion of the nail)

Lunula: pale, half-moon shaped region at the root of Lunula: pale, half-moon shaped region at the root of the nailthe nail

– Part of the nail body that covers the matrix (active Part of the nail body that covers the matrix (active area where new cells form)area where new cells form)

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Cuticle: Narrow band of epidermis attached to the Cuticle: Narrow band of epidermis attached to the surface of the nail just in front of the rootsurface of the nail just in front of the root

– Protects the new cells as they growProtects the new cells as they grow

– Onych/o, ungu/oOnych/o, ungu/o mean nail mean nail

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Medical SpecialtiesMedical Specialties

DermatologistDermatologist– Specializes in diagnosing and treating Specializes in diagnosing and treating

disorders of the skindisorders of the skin

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PathologyPathology

Sebaceous GlandsSebaceous Glands– Acne vulgarisAcne vulgaris

Chronic inflammation of the Chronic inflammation of the skin characterized by skin characterized by pustular eruptions caused by pustular eruptions caused by an overproduction of an overproduction of sebumsebum

Most common type of acneMost common type of acne

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PathologyPathology

– ComedoComedoNon-infected lesion formed Non-infected lesion formed by the buildup of sebum by the buildup of sebum and keratin in a hair follicleand keratin in a hair follicle

– Closed = whiteheadClosed = whitehead– Open = blackheadOpen = blackhead– Deep = pimple (papule)Deep = pimple (papule)– Very deep = cystVery deep = cyst

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PathologyPathology

– SeborrheaSeborrheaAny condition that is characterized by an Any condition that is characterized by an overproduction of sebumoverproduction of sebumSeborrheic dermatitisSeborrheic dermatitis

– Inflammation that causes scaling and itching of Inflammation that causes scaling and itching of upper layers of skinupper layers of skin

– Ex extensive dandruff, cradle capEx extensive dandruff, cradle capSeborrheic keratosisSeborrheic keratosis

– Benign growthBenign growth– Has a waxy “pasted-on” lookHas a waxy “pasted-on” look– Often occurs in the elderlyOften occurs in the elderly

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PathologyPathology

Sweat GlandsSweat Glands– AnhidrosisAnhidrosis

Abnormal absence of sweatingAbnormal absence of sweating– HyperhidrosisHyperhidrosis

Condition of excessive sweatingCondition of excessive sweating– DiaphoresisDiaphoresis

Profuse sweatingProfuse sweatingDue to specific cause such as menopause, shock, Due to specific cause such as menopause, shock, extreme emotion, eating spicy food, etcextreme emotion, eating spicy food, etc

– MiliariaMiliariaAKA heat rash, prickly heatAKA heat rash, prickly heatItchy rash caused by blockage of the sweat glands Itchy rash caused by blockage of the sweat glands by bacteria and dead cellsby bacteria and dead cells

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PathologyPathology

– HairHairFolliculitisFolliculitis

– Inflammation of the hair folliclesInflammation of the hair follicles– Especially common on the limbs and in the Especially common on the limbs and in the

beard areabeard areaHirsutismHirsutism

– Presence of excessive facial and body hair in Presence of excessive facial and body hair in womenwomen

– May be hereditary or caused by hormone May be hereditary or caused by hormone imbalanceimbalance

AlopeciaAlopecia– AKA baldnessAKA baldness– Partial or complete absence of hair from where Partial or complete absence of hair from where

it usually growsit usually grows

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PathologyPathology

NailsNails– ClubbingClubbing

Abnormal curvature of the nailsAbnormal curvature of the nailsCan be hereditary, but may also be related to Can be hereditary, but may also be related to oxygen deficienciesoxygen deficiencies

– KoilonychiaKoilonychia““spooning” of the nailspooning” of the nailOften an indication of iron-deficiency anemiaOften an indication of iron-deficiency anemia

– OnychocryptosisOnychocryptosisAKA ingrown toenailAKA ingrown toenail

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PathologyPathology

– OnychomycosisOnychomycosisFungal infection of a nailFungal infection of a nailMay cause the nail to turn white, May cause the nail to turn white, yellow, green, or black, and yellow, green, or black, and become thick or brittlebecome thick or brittle

– OnychophagiaOnychophagiaAKA “nail biting”AKA “nail biting”

– OnycholysisOnycholysisLoosening of the nail from the nail bedLoosening of the nail from the nail bedOften due to infectionOften due to infection

– ParonychiaParonychiaInflammation and swelling of tissue around the nailInflammation and swelling of tissue around the nail

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PathologyPathology

Skin PigmentationSkin Pigmentation– AlbinismAlbinism

Inherited deficiency or Inherited deficiency or absence of pigment in the absence of pigment in the skin, hair, and irises due to skin, hair, and irises due to a missing enzyme a missing enzyme necessary for the necessary for the production of melaninproduction of melanin

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PathologyPathology

– MelanosisMelanosisAny condition of unusual deposits of black pigment Any condition of unusual deposits of black pigment in the skinin the skin

– VitiligoVitiligoLoss of melanin resulting in Loss of melanin resulting in white areas of the skin, white areas of the skin, usually the face and hands usually the face and hands (autoimmune disorder)(autoimmune disorder)

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PathologyPathology

BruisesBruises– PetechiaePetechiae

Pinpoint hemorrhages Pinpoint hemorrhages (less than 2 mm in (less than 2 mm in diameter)diameter)Sometimes result from Sometimes result from severe feversevere fever

EcchymosisEcchymosisLarger irregular area of Larger irregular area of purplish discolourationpurplish discolourationEx black eye, bruiseEx black eye, bruise

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PathologyPathology

Surface LesionsSurface Lesions– Pathologic change of the tissue due to injury Pathologic change of the tissue due to injury

or diseaseor disease– Described by:Described by:

AppearanceAppearance

LocationLocation

ColourColour

sizesize

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PathologyPathology

– CrustCrustAKA scabAKA scab

Collection of dried serum and cellular debrisCollection of dried serum and cellular debris

– MaculeMaculeDiscoloured, flat spot that is less than 1 cm in Discoloured, flat spot that is less than 1 cm in diameter (ex freckles, flat moles)diameter (ex freckles, flat moles)

– PapulePapuleSmall, raised, red lesion that is less than 1 cm in Small, raised, red lesion that is less than 1 cm in diameter – does not contain pusdiameter – does not contain pus

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PathologyPathology

– NoduleNodule

Solid raised lesion that is Solid raised lesion that is larger than 1 cm and deeper larger than 1 cm and deeper than a papulethan a papule

– PlaquePlaque

Scaly, raised area of closely Scaly, raised area of closely spaced papulesspaced papules

– Ex psoriasisEx psoriasis– ScalesScales

Flakes or dry patches of Flakes or dry patches of excess dead epidermal cellsexcess dead epidermal cells

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PathologyPathology

– VerrucaVerrucaAKA wartAKA wart

Small, hard, skin lesion causedSmall, hard, skin lesion caused by the human papilloma virus by the human papilloma virus

– WhealWhealAKA weltAKA welt

Smooth, slightly elevated area that Smooth, slightly elevated area that itchesitches

Often a symptom of allergic Often a symptom of allergic reaction or insect bitesreaction or insect bites

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PathologyPathology

Fluid-Filled LesionsFluid-Filled Lesions– AbscessAbscess

Closed pocket containing pus Closed pocket containing pus

Caused by bacterial infectionCaused by bacterial infection

– CystCystClosed sac just under the skin containing soft or Closed sac just under the skin containing soft or semisolid materialsemisolid material

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PathologyPathology

– PustulePustuleSmall, circumscribed lesion containing pusSmall, circumscribed lesion containing pusimpetigo, smallpox, etcimpetigo, smallpox, etc

– VesicleVesicleSmall blister containing watery Small blister containing watery fluidfluidLess than 0.5 cm in diameterLess than 0.5 cm in diameter

– BullaBullaLarge blister containing watery Large blister containing watery fluidfluidMore than 0.5 cm in diameterMore than 0.5 cm in diameter

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PathologyPathology

Through the skinThrough the skin– AbrasionAbrasion

Superficial layers of skin are scraped Superficial layers of skin are scraped or rubbed awayor rubbed away

– FissureFissure

Groove or crack in the skinGroove or crack in the skin– LacerationLaceration

Torn and jagged wound or Torn and jagged wound or accidental cutaccidental cut

– Puncture woundPuncture wound

Deep hole made by a sharp objectDeep hole made by a sharp object

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PathologyPathology

UlcerUlcer– Open lesion of the skin or Open lesion of the skin or

mucous membrane resultingmucous membrane resulting in tissue loss around the in tissue loss around the edgesedges

– Decubitous ulcer – pressure Decubitous ulcer – pressure ulcer or bedsoreulcer or bedsore

Area where prolonged Area where prolonged pressure causes tissue pressure causes tissue deathdeath

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PathologyPathology

DermatitisDermatitis– Inflammation of the skinInflammation of the skin

Usually involves redness, itchiness (pruritus), Usually involves redness, itchiness (pruritus), swellingswelling

– EczemaEczemaForm of dermatitis that occurs on the face, neck, Form of dermatitis that occurs on the face, neck, elbows, and kneeselbows, and kneesSkin is red, blistered, or oozingSkin is red, blistered, or oozingEventually can become scaly, brown, and Eventually can become scaly, brown, and thickenedthickened

– Contact DermatitisContact DermatitisLocalized allergic response caused by contact with Localized allergic response caused by contact with an irritant or allergenan irritant or allergen

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PathologyPathology

ErythemaErythema– Redness of the skin due to dilated capillariesRedness of the skin due to dilated capillaries

Ex blush, inflammation, sunburnEx blush, inflammation, sunburn

PyodermaPyoderma– Any acute, inflammatory, pus-forming bacterial skin Any acute, inflammatory, pus-forming bacterial skin

infectioninfection

IchthyosisIchthyosis– Group of hereditary disorders characterized by dry, Group of hereditary disorders characterized by dry,

thickened and scaly skinthickened and scaly skin– Ichthy/o means dry or scalyIchthy/o means dry or scaly

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PathologyPathology

LipedemaLipedema– Chronic swelling due to accumulation of fat and fluid Chronic swelling due to accumulation of fat and fluid

under the skinunder the skin– Commonly occurs between the calf and ankleCommonly occurs between the calf and ankle

PsoriasisPsoriasis– Skin disorder characterized by the occurrence of red Skin disorder characterized by the occurrence of red

papules covered by silvery scales on the elbows, papules covered by silvery scales on the elbows, knees, scalp, back or buttocksknees, scalp, back or buttocks

– Caused by an increase in the rate of basal cell growthCaused by an increase in the rate of basal cell growth

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PathologyPathology

RosaceaRosacea– Chronic, idiopathic conditionChronic, idiopathic condition– Produces redness, tiny pimples, and broken Produces redness, tiny pimples, and broken

blood vessels, often on the faceblood vessels, often on the face

SclerodermaScleroderma– Autoimmune disorderAutoimmune disorder– Connective tissues become thickened or Connective tissues become thickened or

hardenedhardened

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PathologyPathology

UrticariaUrticaria– AKA hivesAKA hives– Wheals caused by an allergic reactionWheals caused by an allergic reaction

XerodermaXeroderma– Dry skinDry skin

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PathologyPathology

Bacterial Skin InfectionsBacterial Skin Infections– Furuncles (Boils)Furuncles (Boils)

large, tender, swollen areas caused by infection large, tender, swollen areas caused by infection around hair follicles or sebaceous glandsaround hair follicles or sebaceous glands

– CellulitisCellulitisAcute, rapidly spreading infection within the Acute, rapidly spreading infection within the connective tissueconnective tissue

Symptoms include malaise, swelling, warmth, and Symptoms include malaise, swelling, warmth, and red streaksred streaks

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PathologyPathology

– ImpetigoImpetigoHighly contagious pyodermaHighly contagious pyoderma

Characterized by isolated pustules that become Characterized by isolated pustules that become crusted and rupturecrusted and rupture

– Necrotizing FasciitisNecrotizing FasciitisAKA flesh-eating bacteriaAKA flesh-eating bacteria

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PathologyPathology

Fungal Skin InfectionsFungal Skin Infections– TineaTinea

AKA ringwormAKA ringworm

Grows on skin, hair or nailsGrows on skin, hair or nails

Fungus spreads out in circle Fungus spreads out in circle leaving normal-looking skin leaving normal-looking skin in the middlein the middle

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PathologyPathology

Parasitic Skin InfectionsParasitic Skin Infections– ScabiesScabies

Caused by infestation with the itch miteCaused by infestation with the itch mite

Produces brown lines and an itchy rashProduces brown lines and an itchy rash

– PediculosisPediculosisInfestation with liceInfestation with lice

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PathologyPathology

Skin GrowthsSkin Growths– CallusCallus

Thickening of the skin caused by repeated rubbingThickening of the skin caused by repeated rubbingA A corncorn is a callus that has developed a hard core is a callus that has developed a hard core

– CicatrixCicatrixScar resulting from the healing of a woundScar resulting from the healing of a woundForms from granulation tissueForms from granulation tissue

– KeloidKeloidAbnormally raised or thickened scar that expands Abnormally raised or thickened scar that expands past the boundaries of the original incisionpast the boundaries of the original incision

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PathologyPathology

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PathologyPathology

Nevus (nevi)Nevus (nevi)– AKA moleAKA mole– Small, dark skin growths that Small, dark skin growths that

develop from melanocytesdevelop from melanocytes– Normally benignNormally benign– Dysplastic nevi are atypical moles that may Dysplastic nevi are atypical moles that may

develop into skin cancer develop into skin cancer

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PathologyPathology

Skin CancerSkin Cancer– Most common form of cancer, but often Most common form of cancer, but often

curablecurableBasal cell carcinomaBasal cell carcinoma

– Slow growing, rarely spreadsSlow growing, rarely spreads– Lesions are pink, smooth, Lesions are pink, smooth,

and raised with a depression and raised with a depression in the center (tend to bleedin the center (tend to bleed easily) easily)

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Squamous Cell Squamous Cell carcinomacarcinoma

Begins as a tumour Begins as a tumour of the squamous of the squamous epithelial cells that epithelial cells that can quickly spreadcan quickly spreadAppears as sores Appears as sores that will not heal or that will not heal or have a crusted, have a crusted, heaped-up lookheaped-up look

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PathologyPathology

– Malignant MelanomaMalignant MelanomaOccurs in the melanocytesOccurs in the melanocytes

Very dangerous and sometimes fatalVery dangerous and sometimes fatal

Signs:Signs:– A – AsymmetryA – Asymmetry– B – Border IrregularityB – Border Irregularity– C – ColourC – Colour– D – DiameterD – Diameter

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PathologyPathology

BurnsBurns– Injury caused by heat, flame, electricity, sun, Injury caused by heat, flame, electricity, sun,

chemicals, radiationchemicals, radiation– Described according to the percentage of total Described according to the percentage of total

body skin affected, as well as the depth body skin affected, as well as the depth (layers of skin involved)(layers of skin involved)

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PathologyPathology

– First Degree: First Degree: no blisters, superficial damage to epidermisno blisters, superficial damage to epidermis

– Second Degree: Second Degree: blisters, damage to epidermis and dermisblisters, damage to epidermis and dermis

– Third Degree: Third Degree: damage to epidermis, dermis, subcutaneous damage to epidermis, dermis, subcutaneous tissue, and possibly underlying muscletissue, and possibly underlying muscle

Varied tissue colour, no response to stimuliVaried tissue colour, no response to stimuli

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Diagnostic ProceduresDiagnostic Procedures

BiopsyBiopsy– Removal of a small piece of tissue for Removal of a small piece of tissue for

examination to confirm or establish a examination to confirm or establish a diagnosisdiagnosis

Incisional – not all of the tumour or lesion is Incisional – not all of the tumour or lesion is removedremoved

Excisional – entire tumor or lesion and a margin of Excisional – entire tumor or lesion and a margin of surrounding tissue are removedsurrounding tissue are removed

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TreatmentTreatment

MedicationsMedications– TopicalTopical

Affects only the area to which it is appliedAffects only the area to which it is applied

– TransdermalTransdermalApplied to unbroken skin to be absorbed Applied to unbroken skin to be absorbed continuouslycontinuously

Has a systemic effectHas a systemic effect

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TreatmentTreatment

Tissue RemovalTissue Removal– CauterizationCauterization

Destruction of tissue by burningDestruction of tissue by burning

– CurettageCurettageRemoval of material from the surface by scrapingRemoval of material from the surface by scraping

– DebridementDebridementRemoval of dirt, foreign objects, damaged tissue, Removal of dirt, foreign objects, damaged tissue, etc from a wound to prevent infection and promote etc from a wound to prevent infection and promote healinghealing

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TreatmentTreatment

– Incision and Drainage (I&D)Incision and Drainage (I&D)Cutting open a lesion and draining the contentsCutting open a lesion and draining the contents

– Moh’s surgeryMoh’s surgeryTechnique of excising skin tumours by removing Technique of excising skin tumours by removing tumour tissue layer-by-layer, examining the tissue, tumour tissue layer-by-layer, examining the tissue, and repeating until entire tumour is removedand repeating until entire tumour is removed

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Skin: The Integumentary System