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