Skin Accessories and Appendages - PowerPoint Presentation

Slide1

Skin Accessories and Appendages

Pages 119-124

Appendages of the Skin

Glandsall exocrine glands (meaning they release secretions via ducts)Sebaceous glandsSweat glandsHair/hair folliclesNails

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Figure

4.3 Skin structure.

Dermal papillae

Hair shaft

Pore

Appendages of skin

•

Eccrine

sweat gland

•

Arrector

pili

muscle

• Sebaceous (oil) gland

• Hair follicle

• Hair root

Cutaneous vascular plexus

Adipose tissue

Epidermis

Dermis

Papillary

layer

Reticular

layer

Hypodermis

(subcutaneous

tissue)

Nervous structures

• Sensory nerve fiber

• Lamellar corpuscle

• Hair follicle receptor

(root hair plexus)

Sebaceous (oil) glands

Produce sebum (oil) which:Lubricates skin/ slows water lossPrevents brittle hairKills bacteriaMost empty into hair follicles; others directly onto skin surfaceHighly active at puberty

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Figure 4.7a

Cutaneous glands.

Eccrine

gland

Sebaceous

gland

Sweat

pore

Sebaceous

gland duct

Dermal connective

tissue

Hair in

hair follicle

Secretory cells

(

a) Photomicrograph of a sectioned

sebaceous gland (100

×

)

Sweat glands

Two types:Eccrine glandsProduce sweat through pores all over skin surfaceSweat has salts, Vit. C, excretory wastes (uric acid)Apocrine glandsDucts empty into hair folliclesActivated at puberty; found in armpit and genital areasSweat that also contains fatty acids and proteins (milky or yellowish color)Bacteria like this stuff – they create body odor when they use it

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Function of sweat

dissipate excess heat (homeostatic)ExcretionInhibits bacterial growth (acidic environment)Make us feel really yucky 

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Figure 4.7b

Cutaneous glands.

Eccrine

gland

Sebaceous

gland

Sweat

pore

Dermal connective

tissue

Eccrine

gland duct

Secretory cells

(b) Photomicrograph of a sectioned

eccrine

gland (205

×

)

hair

Produced by hair follicleOuter tissue= connectiveInner= epithelialRoot is enclosed in the follicleShaft (dead part) projects from surface of scalp or skinConsists of hard keratinized epithelial cellsMelanocytes provide pigment for hair colorHair grows from hair bulb in stratum basale

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Figure 4.8c

Structure of a hair and hair follicle.

Hair

follicle

(c)

Fibrous

sheath

Epithelial

sheath

Hair matrix (growth

zone) in hair bulb

Melanocyte

Subcutaneous

adipose tissue

Hair papilla

containing

blood vessels

Appendages of the Skin

Arrector pili muscle Smooth muscle tissuePulls hairs upright when person is cold or frightened (gives us goosebumps)You could consider this a vestigial structure- it has lost all of its function/use for humans

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Figure 4.8a

Structure of a hair and hair follicle.

Hair

shaft

Arrector

pili

Sebaceous

gland

Hair root

Hair bulb

in follicle

(a)

Appendages of the Skin

Notice how the scale-like cells of the cuticle overlap one another in this hair shaft image (660×)

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Figure

4.9 Scanning electron micrograph showing a hair shaft emerging from a follicle at the skin surface.

Nails

Heavily keratinized = very hardStratum basale is responsible for growthLack of pigment makes them colorlessFunctions:ProtectionToolsScratch an itch!

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Appendages of the Skin

Nail structuresFree edgeBody is the visible attached portionNail folds are skin folds that overlap the edges of the nailGrowth occurs from nail matrixRoot of nail is embedded in skinCuticle is the proximal nail fold that projects onto the nail body

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