specialised tissues Flashcards
hair: summarise the structure and function of hair, recall the development and structure of the hair follicle, and summarise the regulation of hair growth
hair function
protection (e.g. UV, physical - eyelashes), sensation, thermoregulation, communication/sexual attraction
hair types
lanugo, vellus and terminal
lanugo characteristics and location
fine and long, foetal and shed before birth, present in premature babies and anorexia
vellus characteristics and location
short, fine, light-coloured, cover most of body
terminal characteristics and location
longer, thicker, darker, scalp, eyebrows, eyelases, pubic, axillary, beard
terminal hair production
vellus differentiation at puberty by androgens
define hair follicle
invagination of epidermis containing a hair
keratin product of hair follicle structure
cortex, medulla, outer cuticle
where is hair located
everywhere except palms, soles and mucous membranes
structure of pilo-sebaceous unit
hair follicle, hair shaft, erector pili muscle, sebaceous gland (epidermis-derived cells; holocrine secretion produce oily sebum)
areas of pilo-sebaceous unit
infundibulum, isthmus, suprabulbar
infundibulum location
surface of skin to opening of sebaceous glands
isthmus location
gland to insertion of erector pili muscle
suprabulbar location
outer and inner root sheath; inner moulds shape
embryology of hair
input from epidermis (responsible for matrix cells, hair shaft and dermis); contribute to papilla, blood vessels and nerves
