Integumentary System

 Hair root – a knot of sensory nerve endings which wraps around each hair bulb  Hair shaft – part of the hair that projects outside the skin; made mostly of keratin (tough protein produced by kerat  Hair bulb matrix – actively dividing germinal layer

 Epidermal sheath – composed of epithelial cells; inner layer of follicle  Dermal sheath – composed of connective tissue; outer layer of follicle  Connective tissue papilla – protrudes from dermal sheath; provides nutrition

 Melanocytes – cells that produce melanin (pigment responsible for skin & hair color)  Arrector pili – smooth muscle which connects the hair follicle to the dermis Responsible for “goose bumps”

kin-care-101/arrector-pili- muscles

 Cuticle – outer most layer  Cortex – middle layer  Medulla – innermost layer

Damaged cuticle Normal cuticle remy-hair

 Free edge - visible unattached portion  Body – visible attached portion  Root – embedded in the skin; adhered to nail bed  Nail fold – skin that overlaps the nail (lateral and proximal)  Nail bed – composed of epithelial tissue

 Nail matrix – thickened proximal part of the nail bed responsible for nail growth  Lunula – visible part of nail matrix  Cuticle or eponychium – next to proximal nail fold