The Integumentary SystemThe Integumentary System

What is the integumentary What is the integumentary system?system?

An organ systemAn organ systemSeveral tissue types functioning togetherSeveral tissue types functioning together

Largest organ of bodyLargest organ of bodyManyMany functions: functions:

Protection, insulation, cushion, prevent water loss, regulate heat loss, Protection, insulation, cushion, prevent water loss, regulate heat loss, excretion through pores, vitamin D synthesis, sensory inputexcretion through pores, vitamin D synthesis, sensory input

2 Main Regions2 Main Regions

Epidermis

Dermis

EPIDERMIS: 4-5 layersEPIDERMIS: 4-5 layersStratum corneumStratum corneumStratum lucidumStratum lucidumStratum granulosumStratum granulosumStratum spinosumStratum spinosumStratum basaleStratum basale

SUPERFICIALSUPERFICIAL

DEEPDEEP

© 2014 Pearson Education, Inc.

Figure 7.2 The main structural features in epidermis of thin skin.

Dermis

Desmosomes

Melaningranule

Melanocyte

Tactile(Merkel)cell

Sensorynerveending

Dermis

Keratinocytes Dendritic cell

Stratum corneumMost superficial layer; 20–30 layersof dead cells, essentially flatmembranous sacs filled with keratin.Glycolipids in extracellular space.

Stratum granulosumOne to five layers of flattened cells,organelles deteriorating; cytoplasmfull of lamellar granules (releaselipids) and keratohyaline granules.

Stratum spinosumSeveral layers of keratinocytesjoined by desmosomes. Cellscontain thick bundles ofintermediate filaments made ofpre-keratin.

Stratum basaleDeepest epidermal layer; one rowof actively mitotic stem cells;some newly formed cells becomepart of the more superficiallayers.

TOP: Stratum corneumTOP: Stratum corneumStratum corneumMost superficial layer; 20–30 layers of dead cells, essentially flat membranous sacs filled with keratin.Glycolipids in extracellular space.

22ndnd (if present) Stratum (if present) Stratum lucidumlucidum

Thin, clear layerThin, clear layerFlattened dead cells, filled with keratin Flattened dead cells, filled with keratin OnlyOnly in “thick skin”: palms, soles in “thick skin”: palms, soles

Fig. 5-4

33rdrd (if thick skin) (if thick skin) Stratum Stratum granulosumgranulosum

Fig. 5-4

Stratum granulosumOne to five layers of flattened cells,organelles deteriorating; Cytoplasm full of lamellar granules (release lipids) and keratohyaline granules.

44thth Stratum spinosum Stratum spinosumStratum spinosumSeveral layers of keratinocytesjoined by desmosomes. Cells contain thick bundles ofintermediate filaments made ofpre-keratin.

KeratinocytesDendritic cell

55thth (bottom) (bottom) Stratum basaleStratum basale

Stratum basaleDeepest epidermal layer; one row of actively mitotic stem cells;some newly formed cells becomepart of the more superficiallayers.

DesmosomesMelaningranule

Melanocyte

Tactile(Merkel)cell

Sensorynerveending

Dermis

Epidermal cellsEpidermal cellsKeratinocytesKeratinocytes: most abundant, produce keratin: most abundant, produce keratinMelanocytesMelanocytes: produce melanin, shield nuclei from : produce melanin, shield nuclei from

UV, freckle = many in one spotUV, freckle = many in one spotLangerhansLangerhans cellscells: macrophages (immune system) : macrophages (immune system)

that help stimulate a defense; in s. spinosumthat help stimulate a defense; in s. spinosumMerkelMerkel cellscells: sensory touch receptors; in s. basale: sensory touch receptors; in s. basale

Papillary layer Papillary layer superficial, just below the epidermissuperficial, just below the epidermis

Reticular layer Reticular layer deep, below the papillary layerdeep, below the papillary layer

DERMIS: 2 layersDERMIS: 2 layers

© 2014 Pearson Education, Inc.

Figure 7.1 Skin structure.

Hair shaft

Papillarylayer

Reticularlayer

Dermal papillae

Subpapillaryplexus

Sweat pore

• Eccrine sweat gland• Arrector pili muscle• Sebaceous (oil) gland• Hair follicle• Hair root

Cutaneous plexus

Adipose tissue

Appendages of skin

Nervous structures

Epidermis

Dermis

Hypodermis(subcutaneous tissue;not part of skin)

• Sensory nerve fiber with free nerve endings

• Lamellar corpuscle• Hair follicle receptor (root hair plexus)

Dermal papillae (projections) extend from upper Dermal papillae (projections) extend from upper dermis into epidermal ridgesdermis into epidermal ridgesEpidermal ridges formed by stratum basale, at Epidermal ridges formed by stratum basale, at

junction of epidermis & dermis junction of epidermis & dermis FINGERPRINTS! FINGERPRINTS!Areolar tissueAreolar tissue

Papillary LayerPapillary Layer

Thicker layerThicker layerDense irregular connective tissueDense irregular connective tissueFibers Fibers Vascular, glandular (sweat/sebaceous)Vascular, glandular (sweat/sebaceous)Stretch marks: dermis is torn because stretched Stretch marks: dermis is torn because stretched

too far…then repairedtoo far…then repaired

Reticular LayerReticular Layer

Dermal CellsDermal CellsMeissner’s corpusclesMeissner’s corpuscles: light touch receptors in : light touch receptors in

dermis—PAPILLARY LAYERdermis—PAPILLARY LAYER

Pacinian (lamellar) corpusclesPacinian (lamellar) corpuscles: deep pressure : deep pressure receptors in dermis—RETICULAR LAYERreceptors in dermis—RETICULAR LAYER

HypodermisHypodermisDeep to the dermis (below it)Deep to the dermis (below it)Superficial fascia layerSuperficial fascia layerPrimarily adipose tissuePrimarily adipose tissueNOT a part of the “skin”NOT a part of the “skin”

Accessory Skin OrgansAccessory Skin OrgansHairHairNailsNailsCutaneous GlandsCutaneous Glands

Hair follicleHair follicleTubular Tubular

depression in depression in epidermis & epidermis & dermisdermis

Where a hair Where a hair developsdevelops

Follicle wall

Hair bulbHair bulb(root), (root),

within the within the hair hair follicle, follicle, the the enlarged enlarged base base

Hair bulb

Root sheathRoot sheathInner Inner

cylinder of cylinder of epidermis epidermis surrounding surrounding hair root in hair root in the folliclethe follicle

• Internal epithelial root sheath

• External epithelial root sheath

Arrector piliArrector piliSmooth muscle cellsSmooth muscle cellsConnect hair follicle to Connect hair follicle to

papillary layerpapillary layerMuscles contract Muscles contract

hair stands up, hair stands up, goosebumps b/c skin goosebumps b/c skin dimpleddimpled

Arrectorpili muscle

Hair shaftHair shaftVisible, dead Visible, dead

(keratinized) (keratinized) portion of the portion of the hairhair

Hair shaft

Figure 7.6 Photomicrographs of skin.

Hair follicle

Sloughing stratumcorneum cells

Hair shaft

Epidermis

Dermis

Epidermis

Dermis

• Stratum corneum

• Stratum lucidum

• Stratum granulosum

• Stratum spinosum

• Stratum basale

NAILSNAILSAre in the integumentary systemAre in the integumentary systemDon’t need to know the specifics FOR LABDon’t need to know the specifics FOR LAB

Cutaneous GlandsCutaneous GlandsSebaceous GlandsSebaceous Glands

Sweat GlandsSweat GlandsEccrineEccrineApocrineApocrine

Sebaceous GlandsSebaceous Glands““oil glands”oil glands”Associated with hair follicleAssociated with hair follicleSecrete sebum into hair follicle to keep hair from Secrete sebum into hair follicle to keep hair from

being brittle (holocrine gland)being brittle (holocrine gland)Sebaceousgland

Sweat GlandsSweat GlandsExocrine glands, all over body (pores)Exocrine glands, all over body (pores)2 types of fluid:2 types of fluid:

Eccrine glandsEccrine glands Forehead, back, palms, solesForehead, back, palms, soles Clear perspiration (water, salts, urea: exocytosis), controls body Clear perspiration (water, salts, urea: exocytosis), controls body

temperaturetemperature Merocrine glandsMerocrine glands

Apocrine glandsApocrine glands Much Much largerlarger Axillary, pubic, mammary (specialized, produces milk)Axillary, pubic, mammary (specialized, produces milk) ““cloudy” perspiration, odorouscloudy” perspiration, odorous Olfactory communication--pheromonesOlfactory communication--pheromones

Eccrinegland

Skin Model Key:

I. EpidermisII. DermisIII. Hypodermis (subcutaneous)1. Stratum corneum1a. Stratum lucidum2. Stratum germatativum2a. Stratum granulosum2b. Stratum spinosum2c. Stratum basale3. Papillae4. Touch (Meissner) corpuscle5. Adipose tissue6. Laminated (Pacinian) corpuscle7. Sweat (Eccrine) gland8. Hair (longitudinal section)

8a. Medulla8a. Medulla8b. Cortex8b. Cortex8c. Cuticle8c. Cuticle8d. Internal epithelial root sheath8d. Internal epithelial root sheath8e. External or outer epithelial root 8e. External or outer epithelial root sheathsheath8f. Glassy (hyaloid) membrane8f. Glassy (hyaloid) membrane8g. Fibrous connective tissue root 8g. Fibrous connective tissue root sheathsheath9. Hair (cross-section)9. Hair (cross-section)10. Hair shaft10. Hair shaft11. Root11. Root11a. Hair bulb11a. Hair bulb12. Hair papilla12. Hair papilla13. Sebaceous glands13. Sebaceous glands14. Arrector pili muscle14. Arrector pili muscle15. Sweat (apocrine) gland15. Sweat (apocrine) gland15a. Smooth muscle cells15a. Smooth muscle cells15b. Hyaline top15b. Hyaline top15c. Part of the pushed out cell body15c. Part of the pushed out cell body

Interactive website—quiz yourself!http://daphne.palomar.edu/ccarpenter/Models/skin_model_2.htm

Review Figure 7.1