Chapter 4 quiz
arrector pili muscle
moves hair shaft perpendicular to skin; causes goose bumps
hair shaft
part of hair in epidermis and extending body beyond skin surface
hair bulb
part of hair that contains the matrix
hair root
part of hair within dermis
nail matrix
part of nail deep to nail root that produces new cells, causing the nail to grow
free edge
part of nail that extends beyond digit
nail body
part of nail that is visible
nail root
part of nail within skin
melanocytes
produces melanin which shields cell nuclei from UV radiation, compose about 8% of epidermal cells
dermal papillae
projections of dermis that cause epidermal ridges
stratum granulosum
epidermal layer containing visible granules, 3-5 layers of dying keratinocytes
stratum spinosum
appears to have thorn-like projections in prepared slides, 8-10 rows of cells
papillary region
areolar connective tissue layer beneath basement membrane
merkel cells
associated with sensory neurons and functions in sensation of touch, compose about 2% of epidermal cells
dermis
connective tissue layer that is firmly attached to the epidermis by a basement membrane, provides the epidermis with nutrients & connects epidermis to the hypodermis
papilla
connective tissue projection; provides blood supply for hair matrix
lunula
crescent-shaped area of nail body near cuticle
langerhans cells
defends skin against microbes, compose about 2% of epidermal cells
hair follicle
epithelial layer that surrounds hair root
stratum basale
layer of epidermis where there is the most rapid cell division, contains stem cells. Single row of cells attached to the basement membrane
keratinocytes
produce keratin, compose about 90% of epidermal cells
sebaceous gland
secretes sebum onto hair and skin
hyponychium
secures nail to digit
apocrine glands
sudoriferous glands located in axillary and genital areas; become active after puberty
eccrine gland
sudoriferous glands that deposit sweat onto epidermal ridges causing fingerprints
epidermis
the outer layer of skin, composed of epithelial tissue
reticular layer
thick dermal layer containing dense, irregular connective tissue with hair follicles and glands
eponychium
thickened epithelial tissue at proximal end of nail body
stratum corneum
tough, water-repellent epidermal layer; contains dead squamous-shaped cells. thickest, outermost layer 25-30 layers of dead keratinocytes
stratum lucidum
translucent layer found in thick skin, absent in thin skin. 3-5 layers of flat dead keratinocytes