Chapter 5 Part 2 Flashcards
Hair
- Hair itself (also called pili) are flexible strands of dead keratinized cells. Contains hard keratin, not soft keratin like in skin. Hard keratin is durable and the cells won’t flake off. Made in Hair Follicles
- Located everywhere except palms, soles (of feet), lips, nipples, and portions of the external genitalia.
- Functions) Warn of objects on the skin, Guard against trauma (in thick areas), Protect from heat loss and to shield the skin from sunlight.
Regions of the Hair
- Shaft) Area of hair where keratinization is complete. Area that extends above the scalp.
- Root) Area within the scalp where keratinization is still going on.
Shapes of Hair
- If the hair shaft is Flat and Ribbon like the cross section the hair will be Kinky.
- If shaft is oval in the cross section the hair will be wav
- If the shaft is perfectly round the hair will be straight.
Three Parts of the Hair Shaft
- Medulla) Central core of large cells and air spaces and the only part of the hair which has Soft Keratin. It is absent in fine hairs.
- Cortex) Several layers of flattened cells surrounding the medulla.
- Cuticle) Outer layer consisting of overlapping layers (shingles on roof). Heavily keratinized; provides strength and keeps inner layer compact.
Hair Color
- Pigments are made by melanocytes in the hair follicle.
- Combinations of the different colors of melanin (yellow, rust, brown, black) create the hair colors.
- Red hair also has the Pheomelanin pigment. Grey/white hair results when melanin production slows and air bubbles replace melanin in the hair.
Hair Follicle
- (Folli - Bag) Folds down from the epidermal surface into the dermis. Extends from the epidermal surface into the dermis.
- Hair Bulb) Expanded area at the deep end of follicle.
- Hair Follicle Receptor (Root Plexus) sensory nerve endings that wrap around the hair bulb.
- Hair is considered a sensory touch receptor.
Components of the Hair Follicle Wall.
- Peripheral Connective Tissue Sheath) Fibrous sheath derived from the dermis.
- Glassy membrane) thickened basil lamina
- Epithelial Root Sheath) derived from the epidermis.
Hair matrix
- Area of bulb which actively dividing and making cells.
- As the matrix makes new cells it pushes the older ones upward.
Arrector Pili
Small band of smooth muscle attached to the hair follicle. Responsible for goosebumps.
Hair Papilla
-Dermal tissue containing a knot of capillaries that supply nutrients to growing hair. 1
Nail Properties
- Scale like modifications of epidermis that contain hard keratin; protect the distal, dorsal surface of fingers and toes.
- Consist of a free edge, nail plate/body, and root.
- Nail bed is epidermis under the nail.
- Nails appear pink because of
Nail Matrix
-Thickened portion of bed responsible for nail growth.
Nail Folds
-Skin folds that overlap border of the nail
Eponychium
- Also known as a cuticle.
- Is a nail fold that projects onto the surface of the nail body.
Hyponychium
-Area under free edge of nail that accumulates dirt,
Lunula
-Thickened nail matrix, appears white.