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30 terms

anatomy ch5 -2

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lanugo
delicate unpigmented hairs that covers the fetus
terminal hairs
long, course, pigmented h airs that replace lanugo on the scalp, eyebrows, and eyelids
vellus hairs
short, fine, unpigmented hairs that replace lanugo over most of the body
terminal hairs
the t ype of hair that replaced vellus hairs at puberty
shaft
portion of hair protruding above the surface of the skin
hair bulb
an expanded knob at the base of the hair root
medulla
central axis of the hair that consists of two or three layers of cells contraining soft keratin
cortex
forms the bulk of the hair; consists of cells containing hard keratin
cutible
outermost layer of the hair shaft and root, composed of a single overlapping layer of cells containing hard keratin
dermal root sheath
surrounds the epithelial foot sheath
epithelial foot sheath
layer of cells immeditely surrounding the foot of the hair
matrix
mass of undifferentiated epithelial cells inside the hair bulb that produces the hair and internal epithelial root sheath
metalocytes
produce the pigment responsible for hair color
arrector pili
smooth muscle cells that attach to the hair follicle dermal root sheath and the papillary layer of the dermis; cause hair to stand on end
sebum
white substance rich in lipids, which oils the hair and skin surface, prevents drying, and protects against bacteria
sebaceous gland
gland that opens into a hair follicle; produces sebum
merocrine sweat gland
gland that opens to the surface of the skin and secretes an isotonic fluid that is mostly water; involved with temperature regulation
apocrine sweat gland
gland that usually opens into a hair follicle; secretes an organic substance that is metabolized by bacteria to produce body odor
ceruminous gland
gland that produces ear wax
nail root
proximal portion of the nail that is covered by skin
nail fold
portion of the skin that covers the lateral and proximal edges of the nail
nail groove
holds the edges of the nail in place
eponychium
cutible; the stratum corneum of the n ail fold that grows onto the nail body
nail bed
nail root and nail body attach to this structure
nail matrix
proximal portion of the nail bed; produces most of the nail
lunula
whitish, crescent-shaped area at the base of the nail; part of the nail matrix
acne
disorder of the hair follicles and sebaceous glands that involves testosterone and bacteria
wart
viral infection of the epidermis
ringworm and athlete's foot
fungal infections that affect the keratinized portion of the skin
decubitus ulcers
disorder caused by ischemia and necrosis of the hypodermis