Chapter 5.2 Accessory Structures of the Skin

Hair

found on all body parts except the palms, soles, lips, nipples and portions the external reproductive organs

When is there a noticeable hair in axillary and pelvic regions?

after puberty

Hair in different parts of the body has different…?

growing and resting time periods

Hirsutism

excess body hair

Hair follicles

surround the hair within the skin and are formed from epidermal cells

• located in dermis

Hair matrix

where cell division occurs; hair growth center

• cells become keratinized as they are pushed out, away from blood supply

Hair root

portion of hair within follicle

Hair shaft

portion of hair that continues beyond the skin

Alopecia

hair loss

Androgenic alopecia - male pattern baldness; most common form of alopecia

Alopecia areata - sudden onset of patchy hair loss

Sebaceous (oil) glands

secret into follicle

Arrector pili muscle

smooth muscle attached to hair follicle: create goosebumps

nail root

region at base of nail with special epithelial cells that nails grow from

nail body

visible portion of nail

cuticle

fold of skin that hides nail root

How much do nails usually grow a week?

1 milimeter

What causes pink color of nails?

vascularized dermal tissue beneath nail

lunula

whitish color of half-moo-shaped base

• results from the thicker layer of rapidly reproducing cells in this area

glands

groups of cells specialized to produce and secrete a substance into ducts

sweat glands

• also called sudoriferous glands

• present in all regions of skin

• especially active when person is under stress

As many as glands per cm² on the leg, ___ per cm² on palms and soles, and even _______ amounts on fingertips.

90, 400, greater

shape of sweat glands

• tubular

• coiled particularly at origin with dermis

two types of sweat glands

Apocrine glands & Eccrine glands

apocrine glands

open into hair follicles in the anal region, groin and armpits, begin to secrete at puberty

eccrine glands

open onto the surface of the skin, become active when a person is hot, helping lower body temperature as sweat evaporates

ceruminous glands

• modified sweat glands lining opening of ear (external ear canal)

• produce cerumen (earwax)

sebaceous glands

• most associate with a hair follicle

• secret oily substance, sebum, that flows into follicle and then out onto the skin surface

What does the secretion of sebum do?

softens and lubricates hair and skin, helps waterproof both of them

What does sebu do?

weakens or kills bacteria on skin surface because of its low pH, or acidity

What parts of body commonly fail to produce sebum? What does this cause?

• face and back

  • secretions collect and form whiteheads or blackheads

  • if pus-inducing bacteria present, a boil or pimple may result