chapter three: skin structure and growth

arrector pili muscles

small, involuntary muscles in the base of the hair follicle that cause goosebumps

barrier function

complex of lipids that keep the skin moist by preventing water evaporation and guards against irritants penetrating the skins surface; and to help regulate the skin’s pH

broad-spectrum sunscreen

sunscreen product that has been shown to protect from burning, skin cancer, and premature aging; protects against both UVA and UVB radiation from the sun

collagen

fibrous, connective tissue made from protein; that gives the skin form and strength

dermal papillae

membranes of ridges and grooves that attach to the epidermis

dermatologist

physician who specializes in diseases and disorders of the skin, hair and nails

dermatology

medical branch of science that deals with the study of skin and its nature, structure, functions, diseases and treatment

dermis

also known as derma, corium, cutis or true skin; underlying or inner layer of the skin

elastin

protein base similar to collagen that forms elastic tissue

dermal-epidermal junction

top of the papillary layer where it joins the epidermis

epidermis

outermost and thinnest layer of skin, made up of five layers: stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum and stratum germinativum

eumelanin

type of melanin that is dark brown to black in color

hair papillae

cone-shaped elevations at the base of the follicle that fit into the hair bulb; papillae are filled with tissue that contains the blood vessels and cells necessary for hair growth and follicle nourishment

keratin

fibrous protein of cells tof skin, hair and nailshat is also the principal component

melanin

tiny grains of pigment (coloring matter) produced by melanocytes deposited into cells in the stratum germinativum layer of the epidermis and papillary layers of the dermis

melanocytes

cells that produce the dark skin pigment called melanin

motor nerve fibers

fibers of the motor nerves that are distributed to the arrector pili muscles attached to hair follicles; carry impulses from the brain to the muscles

papillary layer

outer layer of the dermis, directly beneath the epidermis

pheomelanin

type of melanin that is red to yellow in color

recticular layer

deeper layer of the dermis that supplies the skin with oxygen and nutrients

sebaceous glands

also known as oil glands; glands connected to hair follicles; secrete sebum

sebum

fatty or oily secretion that lubricates the skin and preserves the softness of the hair

secretory coil

coiled base of the sudoriferous (sweat) gland

secretory nerve fibers

regulate the excretion of perspiration from the sweat glands and control the flow of sebum to the surface of the skin

sensory nerve fibers

fibers of the sensory nerves that react to heat, cold, touch, pressure and pain

stratum corneum

also known as the horny layer; outermostlayer of the epidermis

stratum germinativum

commonly called the basal cell layer, deepest, live layer of the epidermis that produces skin cells and is responsible for growth

stratum granulosum

also known as granular layer, layer of the epidermis composed of cells filled with keratin that resemble granules

stratum lucidum

clear, transparent layer of the epidermis under the stratum corneum

stratum spinosum

also known as the spiny layer of the epidermis just above the stratum germinativum (basal) layer

subcutaneous layer

also known as hypodermis or superficial fascia; consists of subcutaneous (fat) tissue located beneath the dermis

subcutaneous tissue

also known as adipose or subcutis tissue; fatty tissue found below the dermis that gives smoothness and contour to the body, contains fats for energy, and acts as a protective cushion for the skin

sudoriferous glands

also known as sweat glands; excrete perspiration and detoxify the body by excreting excess salt and unwanted chemicals

sweat glands

also known as sudoriferous glands; excrete perspiration and detoxify the body by excreting excess salt and unwanted chemicals

tactile corpuscles

small epidermal structures with nerve endings that are sensitive to touch and pressure