Accessories/appendages

nails, hair, etc

Hair

dead, keratinized cells of hard keratin

not found in palms, soles, lips, nipples, external genitalia

Functions of Hair

insect detectors

physical trauma, heat loss, and sunlight protection (scalp)

Pigments

melanin gives blonde, brunnette, black hair

trichosiderin 

red hair 

gray/white hair

decrease in melanin production

hair follicles

2 layered wall, (epidermis + dermis)

hair shaft (projects from skin)

keratinization is completed

hair root/follicle

keratinization is ongoing

Medulla 

central core, contains soft keratin (like skin)

cortex 

bulky layer surrounding medulla, multi layered 

cuticle

outermost layer, heavily keratinization, single layer of overlapping cells (like shingles on the roof)

Hair Bulb

expanded deep end of follicle

Vellus 

Fine, pale body hair on children & adult females 

terminal

course, long hair of eyebrows and scalp

puberty

this hair type shows up in axillary & pubic regions of males & females