Epidermal and Dermal Cell Functions and Structures

Keratinocytes

Type of epidermal cell that produces keratin

Keratin

A protective protein in the keratinocytes that makes structures (like hair and nails) hard and water resistant

Melanocytes

Type of epidermal cell that produces melanin

Melanin

A pigment that protects the nucleus of keratinocytes from UV radiation damage

Dendritic (Langerhans) cells

Type of epidermal cell that ingests foreign invaders and activates the immune system

Tactile epithelial (Merkel) cells

Type of epidermal cell that combines with nerve endings to make sensory receptors for touch

Dermal papillae

Projections from its surface into the epidermis that contain capillary loops, nerve endings, and touch receptors

Hair

Long filaments made of dead keratinocytes (Pili)

Medulla

Central core layer of a hair made of soft keratin

Cortex

Bulky middle layer of a hair

Cuticle

Single layer of overlapping cells on the outside layer of a hair

Hair follicles

Tubular invaginations in the epidermis that hair grows out of

Arrector pili

Smooth muscle cell bundle that contracts to raise hair upright

Root hair plexus

Nerve fiber endings that perceive touch and wrap around each bulb

Eccrine sweat glands

Most abundant type of sweat glands, located in the palms, forehead, and soles of the feet

Apocrine sweat glands (sudoriferous)

Large sweat glands deep in the dermis that come in during puberty and empty into the hair follicles around the armpits and groin

Ceruminous glands

Modified apocrine glands in the ear canal that make ear wax

Mammary glands

Modified apocrine glands that secrete milk

Macrophages

Immune cells in the dermis that act as a 2nd line of defense by initiating an immune response for invaders that get through the epidermis

Defensins

Antimicrobial proteins secreted by the skin to help kill bacteria

Function of Nose hair

catch and filter large particles and insects as we inhale

Male Pattern Baldness

Genetic condition, most common in males, due to drop in testosterone

Terminal Hair

Long, coarse, pigmented hair found on the scalp, legs, arms, and bodies of males and females.

Vellus Hair

pale, fine body hair of children and adult females, becomes terminal hair in males during puberty

Nail Bed

Portion of the living skin that supports the nail plate as it grows toward the free edge.

Free edge of nail

the portion of the nail that grows out away from the body

nail root (matrix)

in a groove under a small fold of skin at the base of the nail, where nail production occurs

Lunula of nail

the half moon shaped, white area at the base of the nail

Eponychium

cuticle

nail folds

Folds of normal skin that surround the natural nail plate

Exocrine glands

secrete chemical substances into ducts that lead either to other organs or out of the body (4 main types)

sebaceous glands

secrete sebum (oil) into the hair follicles where the hair shafts pass through the dermis

function of sebaceous glands

lubricates skin and hair, kills bacteria

eccrine glands

glands that produce sweat; found over most of the body

eccrine gland function

thermoregulation