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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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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
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
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
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
Layers of the EpidermisLayers of the Epidermis
Figure 5.2b
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
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)
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)
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)
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)
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
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
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
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
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
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
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
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
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
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
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
Hair FollicleHair Follicle
Figure 5.5a
Hair FollicleHair Follicle
Figure 5.5c
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
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
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
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
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
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
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
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
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
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
Skin CancersSkin Cancers
Figure 5.7a–c
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)
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
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
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
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)
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
Rule of NinesRule of Nines
Figure 5.8a
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
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
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