Integ. System - Hair Flashcards
Where does the human body not have hair?
Palms, sides of fingers and toes, sides and soles of feet, lips, portions of external genitalia
What are the functions of hair?
Protection, insulation, detect light touch, guards openings against particles and insects
Hair root plexus
Free nerve endings that detect light touch and movement of the hair shaft
What are the layers of a hair follicle moving laterally?
Hair papilla, matrix, medulla, cortex, cuticle, internal epithelial root sheath, external epithelial root sheath, dermal root sheath
What is the hair matrix and what does it do?
A layer of dividing basal cells that produce the hair structure and push the hair out of the skin
What produces hair color?
Melanocytes at the hair matrix
*Color determined by genes
What are the three types of hair?
Vellus hair, terminal hairs, lanugo
What are vellus hairs?
Soft, fine, peach fuzz hairs that cover the body surface
What are terminal hairs?
Heavy, pigmented hairs that grow after puberty
*Head, eyebrows, eyelashes…
What is lanugo?
Fine, soft hair that covers the body of a fetus or newborn to protect them from amniotic fluid
Describe the first step of the hair growth cycle.
Anagen- growing phase (6-8 years)
Stem cells multiply and the follicle grows deeper into the dermis.
Hair matrix cells multiply and keratinize causing hair to grow upward.
Old club hair may persist temporarily alongside newly growing hair.
Describe the second step of the hair growth cycle.
Catagen- degenerative phase (2-3 weeks)
Hair growth ceases.
Hair bulb keratinizes and forms club hair.
Lower follicle degenerates.
Describe the third step of the hair growth cycle.
Telogen- resting phase (1-3 months)
Dermal papilla has ascended to level of bulge.
Club hair falls out in telogen or next anagen.
