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Skin (Integument) Skin (Integument) Consists of three major regions Consists of three major regions Epidermis – outermost superficial Epidermis – outermost superficial region region Dermis – middle region Dermis – middle region Hypodermis (superficial fascia) – Hypodermis (superficial fascia) – deepest region deepest region

Skin (Integument)

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Skin (Integument). Consists of three major regions Epidermis – outermost superficial region Dermis – middle region Hypodermis (superficial fascia) – deepest region. Hair shaft. Pore. Dermal papillae (papillary layer of dermis). Epidermis. Meissner's corpuscle. Free nerve ending. - PowerPoint PPT Presentation

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Page 1: Skin (Integument)

Skin (Integument)Skin (Integument) Consists of three major regionsConsists of three major regions

Epidermis – outermost superficial regionEpidermis – outermost superficial region Dermis – middle regionDermis – middle region Hypodermis (superficial fascia) – deepest regionHypodermis (superficial fascia) – deepest region

Page 2: Skin (Integument)

Figure 5.1

Epidermis

Dermis

Hypodermis(superficialfascia)

Hair root

Hair shaft

Pore

Dermal papillae (papillary layer of dermis)Meissner's corpuscle

Free nerve endingReticular layer of dermis

Sebaceous (oil) gland

Arrector pili muscleSensory nerve fiberEccrine sweat glandPacinian corpuscle

ArteryVein

Adipose tissue

Hair follicle receptor(root hair plexus)

Hair follicleEccrine sweatgland

Page 3: Skin (Integument)

EpidermisEpidermis Composed of keratinized stratified squamous Composed of keratinized stratified squamous

epithelium, consisting of four distinct cell epithelium, consisting of four distinct cell types and four or five layerstypes and four or five layers

Cell types include keratinocytes, melanocytes, Cell types include keratinocytes, melanocytes, Merkel cells, and Langerhans’ cellsMerkel cells, and Langerhans’ cells

Outer portion of the skin is exposed to the Outer portion of the skin is exposed to the external environment and functions in external environment and functions in protectionprotection

Page 4: Skin (Integument)

Cells of the EpidermisCells of the Epidermis Keratinocytes – produce the fibrous protein Keratinocytes – produce the fibrous protein

keratinkeratin Melanocytes – produce the brown pigment Melanocytes – produce the brown pigment

melaninmelanin Langerhans’ cells – epidermal macrophages Langerhans’ cells – epidermal macrophages

that help activate the immune systemthat help activate the immune system Merkel cells – function as touch receptors in Merkel cells – function as touch receptors in

association with sensory nerve endingsassociation with sensory nerve endings

Page 5: Skin (Integument)

Layers of the EpidermisLayers of the Epidermis

Figure 5.2b

Page 6: Skin (Integument)

Layers of the Epidermis: Layers of the Epidermis: Stratum Basale Stratum Basale

(Basal Layer)(Basal Layer) Deepest epidermal layer firmly attached to the Deepest epidermal layer firmly attached to the

dermisdermis Consists of a single row of the youngest Consists of a single row of the youngest

keratinocyteskeratinocytes Cells undergo rapid division, hence its Cells undergo rapid division, hence its

alternate name, stratum germinativumalternate name, stratum germinativum

Page 7: Skin (Integument)

Cells contain a weblike system of intermediate Cells contain a weblike system of intermediate filaments attached to desmosomesfilaments attached to desmosomes

Melanin granules and Langerhans’ cells are Melanin granules and Langerhans’ cells are abundant in this layerabundant in this layer

Layers of the Epidermis: Layers of the Epidermis: Stratum Spinosum Stratum Spinosum

(Prickly Layer)(Prickly Layer)

Page 8: Skin (Integument)

Thin; three to five cell layers in which drastic Thin; three to five cell layers in which drastic changes in keratinocyte appearance occurs changes in keratinocyte appearance occurs

Keratohyaline and lamellated granules Keratohyaline and lamellated granules accumulate in the cells of this layeraccumulate in the cells of this layer

Layers of the Epidermis: Layers of the Epidermis: Stratum Granulosum Stratum Granulosum

(Granular Layer)(Granular Layer)

Page 9: Skin (Integument)

Thin, transparent band superficial to the Thin, transparent band superficial to the stratum granulosumstratum granulosum

Consists of a few rows of flat, dead Consists of a few rows of flat, dead keratinocyteskeratinocytes

Present only in thick skinPresent only in thick skin

Layers of the Epidermis: Layers of the Epidermis: Stratum Lucidum Stratum Lucidum

(Clear Layer)(Clear Layer)

Page 10: Skin (Integument)

Outermost layer of keratinized cellsOutermost layer of keratinized cells Accounts for three quarters of the epidermal Accounts for three quarters of the epidermal

thicknessthickness Functions include:Functions include:

WaterproofingWaterproofing Protection from abrasion and penetrationProtection from abrasion and penetration Rendering the body relatively insensitive to Rendering the body relatively insensitive to

biological, chemical, and physical assaultsbiological, chemical, and physical assaults

Layers of the Epidermis: Layers of the Epidermis: Stratum Corneum Stratum Corneum

(Horny Layer)(Horny Layer)

Page 11: Skin (Integument)

DermisDermis Second major skin region containing strong, Second major skin region containing strong,

flexible connective tissueflexible connective tissue Cell types include fibroblasts, macrophages, Cell types include fibroblasts, macrophages,

and occasionally mast cells and white blood and occasionally mast cells and white blood cellscells

Composed of two layers – papillary and Composed of two layers – papillary and reticularreticular

Page 12: Skin (Integument)

Layers of the Dermis: Papillary Layers of the Dermis: Papillary LayerLayer

Papillary layerPapillary layer Areolar connective tissue with collagen and elastic Areolar connective tissue with collagen and elastic

fibersfibers Its superior surface contains peglike projections Its superior surface contains peglike projections

called dermal papillaecalled dermal papillae Dermal papillae contain capillary loops, Dermal papillae contain capillary loops,

Meissner’s corpuscles, and free nerve endingsMeissner’s corpuscles, and free nerve endings

Page 13: Skin (Integument)

Layers of the Dermis: Reticular Layers of the Dermis: Reticular LayerLayer

Reticular layerReticular layer Accounts for approximately 80% of the thickness Accounts for approximately 80% of the thickness

of the skinof the skin Collagen fibers in this layer add strength and Collagen fibers in this layer add strength and

resiliency to the skinresiliency to the skin Elastin fibers provide stretch-recoil propertiesElastin fibers provide stretch-recoil properties

Page 14: Skin (Integument)

HypodermisHypodermis Subcutaneous layer deep to the skinSubcutaneous layer deep to the skin Composed of adipose and areolar connective Composed of adipose and areolar connective

tissuetissue

Page 15: Skin (Integument)

Skin ColorSkin Color Three pigments contribute to skin colorThree pigments contribute to skin color

Melanin – yellow to reddish-brown to black Melanin – yellow to reddish-brown to black pigment, responsible for dark skin colorspigment, responsible for dark skin colors

Freckles and pigmented moles – result from local accumulations of Freckles and pigmented moles – result from local accumulations of melaninmelanin

Carotene – yellow to orange pigment, most Carotene – yellow to orange pigment, most obvious in the palms and soles of the feetobvious in the palms and soles of the feet

Hemoglobin – reddish pigment responsible for the Hemoglobin – reddish pigment responsible for the pinkish hue of the skinpinkish hue of the skin

Page 16: Skin (Integument)

Sweat GlandsSweat Glands Different types prevent overheating of the Different types prevent overheating of the

body; secrete cerumen and milkbody; secrete cerumen and milk Eccrine sweat glands – found in palms, soles of the Eccrine sweat glands – found in palms, soles of the

feet, and foreheadfeet, and forehead Apocrine sweat glands – found in axillary and Apocrine sweat glands – found in axillary and

anogenital areasanogenital areas Ceruminous glands – modified apocrine glands in Ceruminous glands – modified apocrine glands in

external ear canal that secrete cerumenexternal ear canal that secrete cerumen Mammary glands – specialized sweat glands that Mammary glands – specialized sweat glands that

secrete milksecrete milk

Page 17: Skin (Integument)

Sebaceous GlandsSebaceous Glands Simple alveolar glands found all over the bodySimple alveolar glands found all over the body Soften skin when stimulated by hormonesSoften skin when stimulated by hormones Secrete an oily secretion called sebumSecrete an oily secretion called sebum

Page 18: Skin (Integument)

HairHair Filamentous strands of dead keratinized cells Filamentous strands of dead keratinized cells

produced by hair folliclesproduced by hair follicles Contains hard keratin which is tougher and more Contains hard keratin which is tougher and more

durable than soft keratin of the skindurable than soft keratin of the skin Made up of the shaft projecting from the skin, Made up of the shaft projecting from the skin,

and the root embedded in the skinand the root embedded in the skin Consists of a core called the medulla, a cortex, Consists of a core called the medulla, a cortex,

and an outermost cuticleand an outermost cuticle Pigmented by melanocytes at the base of the hairPigmented by melanocytes at the base of the hair

Page 19: Skin (Integument)

Hair Function and DistributionHair Function and Distribution Functions of hair include:Functions of hair include:

Helping to maintain warmthHelping to maintain warmth Alerting the body to presence of insects on the skin Alerting the body to presence of insects on the skin Guarding the scalp against physical trauma, heat Guarding the scalp against physical trauma, heat

loss, and sunlightloss, and sunlight

Page 20: Skin (Integument)

Hair Function and DistributionHair Function and Distribution Hair is distributed over the entire skin surface Hair is distributed over the entire skin surface

except:except: Palms, soles, and lipsPalms, soles, and lips Nipples and portions of the external genitaliaNipples and portions of the external genitalia

Page 21: Skin (Integument)

Hair FollicleHair Follicle Root sheath extending from the epidermal Root sheath extending from the epidermal

surface into the dermissurface into the dermis Deep end is expanded forming a hair bulbDeep end is expanded forming a hair bulb A knot of sensory nerve endings (a root hair A knot of sensory nerve endings (a root hair

plexus) wraps around each hair bulbplexus) wraps around each hair bulb Bending a hair stimulates these endings, hence Bending a hair stimulates these endings, hence

our hairs act as sensitive touch receptorsour hairs act as sensitive touch receptors

Page 22: Skin (Integument)

Hair FollicleHair Follicle

Figure 5.5a

Page 23: Skin (Integument)

Hair FollicleHair Follicle

Figure 5.5c

Page 24: Skin (Integument)

Types of HairTypes of Hair Vellus – pale, fine body hair found in children Vellus – pale, fine body hair found in children

and the adult female and the adult female Terminal – coarse, long hair of eyebrows, Terminal – coarse, long hair of eyebrows,

scalp, axillary, and pubic regionsscalp, axillary, and pubic regions

Page 25: Skin (Integument)

Hair Thinning and BaldnessHair Thinning and Baldness Alopecia – hair thinning in both sexesAlopecia – hair thinning in both sexes True, or frank, baldness True, or frank, baldness

Genetically determined and sex-influenced Genetically determined and sex-influenced condition condition

Male pattern baldness – caused by follicular Male pattern baldness – caused by follicular response to DHTresponse to DHT

Page 26: Skin (Integument)

Structure of a NailStructure of a Nail Scalelike modification of the epidermis on the Scalelike modification of the epidermis on the

distal, dorsal surface of fingers and toesdistal, dorsal surface of fingers and toes

Figure 5.6

Page 27: Skin (Integument)

Functions of the Integumentary Functions of the Integumentary SystemSystem

Protection – chemical, physical, and mechanical Protection – chemical, physical, and mechanical barrierbarrier

Body temperature regulation is accomplished by:Body temperature regulation is accomplished by: Dilation (cooling) and constriction (warming) of Dilation (cooling) and constriction (warming) of

dermal vesselsdermal vessels Increasing sweat gland secretions to cool the body Increasing sweat gland secretions to cool the body

Cutaneous sensation – exoreceptors sense touch Cutaneous sensation – exoreceptors sense touch and painand pain

Page 28: Skin (Integument)

Functions of the Integumentary Functions of the Integumentary SystemSystem

Metabolic functions – synthesis of vitamin D Metabolic functions – synthesis of vitamin D in dermal blood vesselsin dermal blood vessels

Blood reservoir – skin blood vessels store up Blood reservoir – skin blood vessels store up to 5% of the body’s blood volumeto 5% of the body’s blood volume

Excretion – limited amounts of nitrogenous Excretion – limited amounts of nitrogenous wastes are eliminated from the body in sweatwastes are eliminated from the body in sweat

Page 29: Skin (Integument)

Skin CancerSkin Cancer Most skin tumors are benign and do not Most skin tumors are benign and do not

metastasizemetastasize A crucial risk factor for nonmelanoma skin A crucial risk factor for nonmelanoma skin

cancers is the disabling of the cancers is the disabling of the p53p53 gene gene Newly developed skin lotions can fix damaged Newly developed skin lotions can fix damaged

DNADNA

Page 30: Skin (Integument)

Skin CancerSkin Cancer The three major types of skin cancer are:The three major types of skin cancer are:

Basal cell carcinomaBasal cell carcinoma Squamous cell carcinomaSquamous cell carcinoma MelanomaMelanoma

Page 31: Skin (Integument)

Basal Cell CarcinomaBasal Cell Carcinoma Least malignant and most common skin cancerLeast malignant and most common skin cancer Stratum basale cells proliferate and invade the Stratum basale cells proliferate and invade the

dermis and hypodermisdermis and hypodermis Slow growing and do not often metastasizeSlow growing and do not often metastasize Can be cured by surgical excision in 99% of Can be cured by surgical excision in 99% of

the casesthe cases

Page 32: Skin (Integument)

Squamous Cell CarcinomaSquamous Cell Carcinoma Arises from keratinocytes of stratum spinosumArises from keratinocytes of stratum spinosum Arise most often on scalp, ears, and lower lipArise most often on scalp, ears, and lower lip Grows rapidly and metastasizes if not removedGrows rapidly and metastasizes if not removed Prognosis is good if treated by radiation Prognosis is good if treated by radiation

therapy or removed surgicallytherapy or removed surgically

Page 33: Skin (Integument)

MelanomaMelanoma Cancer of melanocytes is the most dangerous Cancer of melanocytes is the most dangerous

type of skin cancer because it is:type of skin cancer because it is: Highly metastaticHighly metastatic Resistant to chemotherapyResistant to chemotherapy

Page 34: Skin (Integument)

Skin CancersSkin Cancers

Figure 5.7a–c

Page 35: Skin (Integument)

MelanomaMelanoma Melanomas have the following characteristics Melanomas have the following characteristics

(ABCD rule)(ABCD rule) A: Asymmetry; the two sides of the pigmented A: Asymmetry; the two sides of the pigmented

area do not match area do not match B: Border is irregular and exhibits indentationsB: Border is irregular and exhibits indentations C: Color (pigmented area) is black, brown, tan, C: Color (pigmented area) is black, brown, tan,

and sometimes red or blueand sometimes red or blue D: Diameter is larger than 6 mm (size of a pencil D: Diameter is larger than 6 mm (size of a pencil

eraser)eraser)

Page 36: Skin (Integument)

MelanomaMelanoma Treated by wide surgical excision Treated by wide surgical excision

accompanied by immunotherapyaccompanied by immunotherapy Chance of survival is poor if the lesion is over Chance of survival is poor if the lesion is over

4 mm thick4 mm thick

Page 37: Skin (Integument)

BurnsBurns First-degree – only the epidermis is damagedFirst-degree – only the epidermis is damaged

Symptoms include localized redness, swelling, Symptoms include localized redness, swelling, and painand pain

Page 38: Skin (Integument)

BurnsBurns Second-degree – epidermis and upper Second-degree – epidermis and upper

regions of dermis are damagedregions of dermis are damaged Symptoms mimic first degree burns, but Symptoms mimic first degree burns, but

blisters also appearblisters also appear

Page 39: Skin (Integument)

BurnsBurns Third-degree – entire thickness of the skin is Third-degree – entire thickness of the skin is

damageddamaged Burned area appears gray-white, cherry red, or Burned area appears gray-white, cherry red, or

black; there is no initial edema or pain (since black; there is no initial edema or pain (since nerve endings are destroyed)nerve endings are destroyed)

Page 40: Skin (Integument)

Rule of NinesRule of Nines Estimates the severity of burnsEstimates the severity of burns Burns considered critical if:Burns considered critical if:

Over 25% of the body has second-degree burnsOver 25% of the body has second-degree burns Over 10% of the body has third-degree burnsOver 10% of the body has third-degree burns There are third-degree burns on face, hands, or feetThere are third-degree burns on face, hands, or feet

Page 41: Skin (Integument)

Rule of NinesRule of Nines

Figure 5.8a

Page 42: Skin (Integument)

Developmental Aspects of the Developmental Aspects of the Integument: FetalIntegument: Fetal

Epidermis develops from ectodermEpidermis develops from ectoderm Dermis and hypodermis develop from Dermis and hypodermis develop from

mesodermmesoderm Lanugo – downy coat of delicate hairs Lanugo – downy coat of delicate hairs

covering the fetuscovering the fetus Vernix caseosa – substance produced by Vernix caseosa – substance produced by

sebaceous glands that protects the skin of the sebaceous glands that protects the skin of the fetus in the amnionfetus in the amnion

Page 43: Skin (Integument)

Developmental Aspects of the Developmental Aspects of the Integument: Adolescent to AdultIntegument: Adolescent to Adult

Skin and hair become oilier and acne may Skin and hair become oilier and acne may appearappear

Skin shows the effects of cumulative Skin shows the effects of cumulative environmental assaults around age 30environmental assaults around age 30

Scaling and dermatitis become more commonScaling and dermatitis become more common

Page 44: Skin (Integument)

Developmental Aspects of the Developmental Aspects of the Integument: Integument:

Old AgeOld Age Epidermal replacement of cells slows and skin Epidermal replacement of cells slows and skin

becomes thinnerbecomes thinner Skin becomes dry and itchySkin becomes dry and itchy Subcutaneous fat layer diminishes, leading to Subcutaneous fat layer diminishes, leading to

intolerance of coldintolerance of cold Decreased elasticity and loss of subcutaneous tissue Decreased elasticity and loss of subcutaneous tissue

leads to wrinklesleads to wrinkles Decreased numbers of melanocytes and Langerhans’ Decreased numbers of melanocytes and Langerhans’

cells increase the risk of skin cancercells increase the risk of skin cancer