Copyright © 2010 Pearson Education, Inc. Figure 5.1 Skin structure. Epidermis Hair shaft Dermis Reticular layer Papillary layer Hypodermis (superficial

Copyright © 2010 Pearson Education, Inc.

Figure 5.1 Skin structure.

Epidermis

Hair shaft

Dermis Reticularlayer

Papillarylayer

Hypodermis(superficial fascia)

Dermal papillae

Pore

Subpapillaryvascular plexus

Appendagesof skin • Eccrine sweat gland• Arrector pili muscle• Sebaceous (oil) gland• Hair follicle• Hair rootNervous structures

• Sensory nerve fiber• Pacinian corpuscle• Hair follicle receptor (root hair plexus)

Cutaneous vascularplexus

Adipose tissue


Figure 5.2 The main structural features of the skin epidermis.

Melanocyte

Melanin granule

Tactile(Merkel)cellSensorynerve ending

Epidermaldendritic cell

Dermis

Dermis

Keratinocytes

Desmosomes

(b)

(a)

Stratum corneumMost superficial layer; 20–30 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space.

Stratum granulosumThree to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated gran-ules (release lipids) and keratohyaline granules.

Stratum spinosumSeveral layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin.

Stratum basaleDeepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. See occasional melanocytes and epidermal dendritic cells.


Figure 5.2a The main structural features of the skin epidermis.

Dermis

Stratum corneumMost superficial layer; 20–30 layers of deadcells represented only by flat membranoussacs filled with keratin. Glycolipids inextracellular space.

Stratum granulosumThree to five layers of flattened cells,organelles deteriorating; cytoplasm full oflamellated granules (release lipids) andkeratohyaline granules.

Stratum spinosumSeveral layers of keratinocytes unified bydesmosomes. Cells contain thick bundles ofintermediate filaments made of pre-keratin.

Stratum basaleDeepest epidermal layer; one row of activelymitotic stem cells; some newly formed cellsbecome part of the more superficial layers.See occasional melanocytes and epidermaldendritic cells.(a)


Figure 5.2b The main structural features of the skin epidermis.

MelanocyteMelanin granule

Tactile(Merkel) cell

Sensorynerve ending Epidermal

dendritic cell

Dermis

KeratinocytesStratum corneumMost superficial layer; 20–30 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space.

Stratum granulosumThree to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules.

Stratum spinosumSeveral layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin.

Stratum basaleDeepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. See occasional melanocytes and epidermal dendritic cells.

Desmosomes

(b)


Figure 5.3 The two regions of the dermis.

Dermis

(a) Light micrograph of thick skin identifying the extent of the dermis, (50x)

(b) Papillary layer of dermis, SEM (22,700x)

(c) Reticular layer of dermis, SEM (38,500x)


Figure 5.3a The two regions of the dermis.

Dermis

(a) Light micrograph of thick skin identifying the extent of the dermis, (50x)


Figure 5.3b The two regions of the dermis.


Figure 5.3c The two regions of the dermis.


Figure 5.4 Dermal modifications result in characteristic skin markings.

Friction ridges

(a)

(b)

Openings ofsweat gland ducts


Figure 5.5 Cutaneous glands.

(a) Photomicrograph of a sectioned sebaceous gland (220x)

(b) Photomicrograph of a sectioned eccrine gland (220x)

Sebaceousgland duct

Hair inhair follicle

Secretory cells

Dermalconnectivetissue


Duct

Sebaceousgland

Sweat pore

Eccrinegland


Figure 5.5a Cutaneous glands.

(a) Photomicrograph of a sectioned sebaceous gland (220x)

Sebaceousgland ductHair inhair follicleSecretory cells


Sebaceousgland

Sweatpore

Eccrinegland


Figure 5.5b Cutaneous glands.

(b) Photomicrograph of a sectioned eccrine gland (220x)

Secretory cells

Dermal connectivetissue

DuctSebaceousgland

Sweat pore

Eccrinegland


Figure 5.6a Structure of a hair and hair follicle.

Hair shaft

ArrectorpiliSebaceousglandHair root

Hair bulb

(a) Diagram of a cross section of a hair within its follicle

• Connective tissue root sheath• Glassy membrane• External epithelial root sheath• Internal epithelial root sheath

Follicle wall

• Cuticle• Cortex• Medulla

Hair


Figure 5.6b Structure of a hair and hair follicle.

(b) Photomicrograph of a cross section of a hair and hair follicle (250x)

• Connective tissue root sheath

Follicle wall

• Cuticle

• Glassy membrane

• Cortex• Medulla

• Internal epithelial root sheath

• External epithelial root sheath

Hair

Hair shaft


Hair bulb


Hair shaft

ArrectorpiliSebaceousglandHair root Hair bulb

(c) Diagram of a longitudinal view of the expanded hairbulb of the follicle, which encloses the matrix

• Internal epithelial root sheath• External epithelial root sheath

• Connective tissue root sheathFollicle wall

Hair matrix

MelanocyteHair papilla

Subcutaneous adipose tissue

• Medulla• Cortex• Cuticle

• Glassy membrane

Hair root

Figure 5.6c Structure of a hair and hair follicle.


Figure 5.6d Structure of a hair and hair follicle.

(d) Photomicrograph of longitudinal view of the hair bulb in the follicle (160x)

Follicle wall

Hair matrix

Hair papilla

Subcutaneousadipose tissue

Hair root

• Connective tissue root sheath• Glassy membrane• External epithelial root sheath• Internal epithelial root sheath

• Cuticle• Cortex• Medulla

Hair shaft


Hair bulb


Figure 5.7 Structure of a nail.

Lateralnail fold

Lunule

Nailmatrix

Root of nail

Proximalnail fold

Hyponychium

Nail bed

Phalanx (bone of fingertip)

Eponychium(cuticle)

Bodyof nail

Free edgeof nail

(a)

(b)


Figure 5.8 Photographs of skin cancers.


Figure 5.9 Estimating the extent and severity of burns using the rule of nines.

Anterior and posteriorhead and neck, 9%

41/2%41/2%

Anterior and posteriorupper limbs, 18%

Anterior and posteriorlower limbs, 36%

100%

Totals

Anterior and posteriortrunk, 36%

Anteriortrunk,18%

9% 9%(Perineum, 1%)

41/2%


Figure 5.10 Partial thickness and full thickness burns.

(a) Skin bearing partialthickness burn (1st and 2nd degree burns)

(b) Skin bearing fullthickness burn(3rd degree burn)

1st degreeburn

2nd degreeburn

3rddegreeburn


Making Connections 5.1 Homeostatic Interrelationships Between the Integumentary System and Other Body Systems

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Copyright © 2010 Pearson Education, Inc. Figure 5.1 Skin structure. Epidermis Hair shaft Dermis Reticular layer Papillary layer Hypodermis (superficial