SKIN ACCESSORIES AND APPENDAGES

Pages 119-124

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APPENDAGES OF THE SKIN

all exocrine glands (secretions via ducts)

Sebaceous glands Sweat glands

Hair/hair follicles Nails

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

Papillarylayer

Reticularlayer

Hypodermis(subcutaneoustissue)

Nervous structures• Sensory nerve fiber• Lamellar corpuscle• Hair follicle receptor (root hair plexus)

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SEBACEOUS (OIL) GLANDS

Produce sebum (oil) which: Lubricates skin/ slows water loss Prevents brittle hair Kills bacteria Highly active at puberty

FIGURE 4.7A CUTANEOUS GLANDS.

Eccrinegland

Sebaceousgland

Sweatpore

Sebaceousgland duct

Dermal connectivetissue

Hair inhair follicle

Secretory cells

(a) Photomicrograph of a sectioned sebaceous gland (100×)

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SWEAT GLANDS (SUDORIFEROUS GLANDS) Two types:

Eccrine glands Produce sweat through pores all over skin surface Sweat has salts, Vit. C, excretory wastes (uric acid)

Apocrine glands Ducts empty into hair follicles Activated at puberty; found in armpit and genital

areas Sweat that also contains fatty acids and proteins (milky

or yellowish color) Bacteria like this stuff – they create body odor when they use it

FIGURE 4.7B CUTANEOUS GLANDS.

EccrineglandSebaceous

gland

Sweatpore

Dermal connectivetissueEccrinegland duct

Secretory cells

(b) Photomicrograph of a sectioned eccrine gland (205×)

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HAIR

Produced by hair follicle Outer tissue= connective Inner= epithelial

Root is enclosed in the follicle Shaft (dead part) projects from surface of

scalp or skin Consists of hard keratinized epithelial cells Melanocytes provide pigment for hair color

Hair grows from hair bulb in stratum basale

FIGURE 4.8C STRUCTURE OF A HAIR AND HAIR FOLLICLE.

Hairfollicle

(c)

FibroussheathEpithelialsheath

Hair matrix (growthzone) in hair bulbMelanocyte

Subcutaneousadipose tissue

Hair papillacontainingblood vessels

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APPENDAGES OF THE SKIN

Arrector pili muscle Smooth muscle tissue Pulls 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

CONTRACTION OF THE ARRECTOR PILI

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NAILS

Heavily keratinized = very hard Stratum basale is responsible for growth Lack of pigment makes them colorless Growth is similar to that of hair

Functions: Protection Tools Scratch an itch!