Hair Flashcards
Terminal (Type)
long, coarse, heavily pigmented hairs.
Velus (Type)
“peach fuzz” short, fine, pale hairs that are barely visible to the naked eye. during adulthood 95% of hair on males is terminal and 5% is velus versus females 35% terminal hair and 65% velus hairs.
Lanugo (Type)
found on fetuses, produced during the 5th month of pregnancy. very fine, non-pigmented, downy hairs. prior to birth the hair of the eyebrows, eyelashes, and scalp are replaced by terminal hairs and the rest velus.
Follicle
made of an external root sheath and an internal root sheath. internal root sheath is produced by the matrix. where hair growth takes place.
Root
portion of the hair deep to the shaft that penetrates into the dermis, and sometimes into the subcutaneous layer. connected to a sebaceous gland. anchors the hair in its follicle.
Medulla
innermost layer of the hair shaft. found in terminal hair. made up of moderately keratinized cells making it the weakest layer of the hair shaft.
Cortex
middle layer of the hair shaft. thickest layer of the hair shaft. keratinized cells which provide strength. also contains melanin granules which give it its color. function is to provide support and strength for the hair.
Cuticle
outermost layer of the hair shaft. made up of flat overlapping cells. gives hair its shape and helps keep it untangled. 8-10 layers of cells. can be damaged by heat and chemicals. made of dead cells. protects the inner layers.
Bulb
base of each hair follicle. onion shaped structure. houses the papilla of the hair, which contains areolar connective tissue and many blood vessels that nourish the growing hair follicle. also contains a germinal layer of cells called the hair matrix.
Hair Matrix
located in the bulb (comes from the stratum basale, the site of cell division.) hair matrix is responsible for the growth of existing hairs when old hairs are shed. also produces cells of the internal root sheath.
