Hair, Skin Color, and Nails A&P 1

Pili

• hair

• has 2 parts, shaft and root

Hair Follicle

• a structure in the dermis made of keratinized cells

• the body and root of the hair follicle is found in the dermis

• they receive nutrients from blood vessels and connect to oil glands

• originate from epidermis

Hair Shaft

• superficial portion of shaft (projects from skin)

Hair Root

• below the surface of the skin

• penetrates into dermis and even hypodermis

• 3 layers- medulla, cortex, cuticle

Hair Bulb

• the swelling at the base of each follicle

• contains matrix (mitotically active cells) and papilla (blood vessels for nutrition)

Arrector Pili (piloerector muscle)

• bundles of smooth muscle cells that extends from upper dermis to the side of hair follicle

• goose bumps!!

Hair Receptors

• nerve fibers that entwine each follicle

• responds to hair movement

Skin Color

• 3 pigments- melanin, carotene, hemoglobin.

Melanin

• pale beige to tan to black pigments

• people of different skin colors have the same number of melanocytes

• dark skinned people- produces greater quantities of melanin, which breaks down more slowly

• light skinned people- produces greater quantities less melanin, which breaks down faster

Skin Pigmentation

• coloration of skin depends on amount of melanin produced in stratum basale and taken up by keratinocytes

Melanocytes

• makes melanin

Freckles and Age Spots

• form when melanin accumulates in patches

Carotene

• a yellow orange pigment that give egg yolk and carrots their color

• converts to vitamin A

• found in stratum corneum and fatty areas of the dermis and subcutaneous layer

Hemoglobin

• red pigment of erythrocytes

• adds reddish, pinkish hue o skin

Nail

• accessory of the integumentary system

• plates of tightly packed, hard, keratinized cells of the epidermis

• approximately 1mm of growth per week

Nail Body

• portion of the nail that’s visible

Free Edge

• part that extends past end of finger or toe

Nail Root

• portion not visible

Lunula

• white ish semilunar area near the nail root

Nail Matrix

• nail growth is caused by the transformation of the superficial cells of this matrix into nail cells

Cuticle

• made up of stratum corneum