Hair Flashcards
What is hair (pili)
-small filamentous structures
-protrude from surface of skin over entire body except for thick skin, lips, and external genitalia
What does hair do
-protection by preventing substances and organisms from entering eyes and nose
-protects skin of scalp from UV radiation and mechanical trauma
-associated with small sensory neuron and plays role in detecting changes in environment
What is hair composed of
-composed of shaft, root, matrix, medulla, cortex, and cuticle
Describe the shaft
Shaft: portion of hair projecting from skin’s surface; made of dead keratinized epithelial cells
Describe root
Root: segment of hair in dermis; surrounded by sensory neuron; epithelial cells are alive; has not completed keratinization process
What does the dermal root sheath do
-surrounds epithelial root
-has connective tissue
-supports follicle and separates it from dermis
What do arrector pili muscles do
-small bands of smooth muscle
-attaches to dermal root sheath on one end and dermal papillary layer on other
-contraction of arrector pili causes hair to stand up (piloerection)
-gives skin dimpled appearance (goosebumps)
Describe inner medulla
-soft core that is found in thick hair (head)
-composed of soft keratin
Describe middle cortex
-highly structured and organized with several layers of keratinocytes
-has hard keratin
-provides strength
Describe cuticle
-single layer overlapping keratinocytes
-has hard keratin
-provides mechanical strength
Describe matrix
small number of keratinocytes at base of root; actively divide
