Biology
Chap 5
Terms
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- Hair follicles
- fold down from epidermal surface into dermis. Scalp (sometimes hypodermis)
- Hair Bulb
- deep end of follicle
- Hair follicle receptor (root hair plexus)
- sensory nerve, wraps around each hair bulb.
- Hair papilla
- dermal tissue protrudes into hair bulb, knot of capillaries supplies nutrients and signals hair to grow.
- Connective tissue root sheath (outer)
- from dermis, wall of hair follicle.
- Glassy membrane
- thickened basement membrane, holds everything inside, separates epidermis from dermis
- Epithelial root sheath (inner)
- invagination of epidermis. Has an inner and external part. Thins to single layer of epithelial cells that covers papilla
- Hair matrix
- actively dividing area of the hair bulb that produces the hair. Originates from hair bulge, has melanocytes.
- Arrector pili
- bundle of smooth muscle cells, contracts and pulls hair upright (goose bumps).
- Hair production
- Chemical signals diffuse from papilla to hair bulge; cells migrate towards papilla then divide to make hair cells. New hair cells produced by matrix, old part is pushed up and fused cells become keratinized and die.