A&P Chapter 7

Epidermis

Outermost layer; stratified squamous epithelial tissue; no blood vessels; oxygen and nutrients are received by diffusion.

Dermis

Inner, deeper layer; composed of connective tissue; contains blood vessels, sweat glands, sebaceous glands, and nerve endings.

Hypodermis

Subcutaneous tissue; loose connective tissue (aerolar) and adipose; binds the skin to the underlying tissue.

Stratum Basale

Basal layer; the innermost layer; columnar stem cells that continually undergo mitosis.

Keratin

A tough, fibrous protein produced by cells as they are pushed upward in the epidermis.

Stratum Corneum

Outermost layer of the epidermis; all cells are dead; up to 30 layers of dead cells make skin durable and resistant to abrasions.

Melanocytes

Cells that produce melanin, which protects the nucleus from ultraviolet (UV) exposure.

Functions of the Skin

Includes protection, barrier, vitamin D production, sensory perception, and thermoregulation.

Sebaceous Gland

Secretes sebum, a type of oil that keeps the skin from drying out; opens into the hair follicle.

Hair Follicle

Sheath of epidermal tissue that provides nerves and blood supply to the hair.

Arrector pil

Small bundle of smooth muscle that contracts in cold temperatures and fear, causing hair to stand up.

Hair Growth

New cells are produced and filled with keratin; hair usually lives about 2-6 years before falling out.

hair shaft

visible part of the hair

Nail Body

The visible part of the nail.

Lunula

The crescent-shaped white area at the base of the nail.

Eccrine Glands

Sweat glands widespread over the body; helps maintain core temperature and eliminate waste.

Apocrine Gland

Sweat glands located mainly in the groin region; function at puberty and respond to stress and sexual stimulation.

Ceruminous Glands

Glands in the external ear canal that secrete cerumen (ear wax) to keep the ear canal from drying out.

First-Degree Burn

Partial-thickness burn involving only the epidermis; causes redness, slight swelling, and pain.

Second-Degree Burn

Partial-thickness burn involving the epidermis and part of the dermis; results in blisters, severe pain, and swelling.

Third-Degree Burn

Full-thickness burn extending into the subcutaneous layer; may appear white or black and leathery.

Alopecia

Excessive hair loss.

Eumelanin

A type of melanin that contributes to darker hair color.

Pheomelanin

A type of melanin that contributes to blond hair color.

Cuticle

Fold of skin that surrounds the nail body.

Nail Bed

Layer of epithelial tissue under the nail; appears pink due to rich blood supply.

Hair Bulb

Lowest part of the hair where growth occurs.

Papilla

Base of the hair; a cluster of connective tissue and blood vessels.

ceruminous glands

modified sweat glands, located in external ear canal, secretes cerumen (earwax)

Sebaceous glands

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

Eccrine glands

glands that produce sweat; found over most of the body

Apocrine glands

Sweat glands in the pubic and underarm areas that secrete thicker sweat, that produce odor when come in contact with bacteria on the skin

Hair shape

based on follicle shape

male pattern baldness

a common hair-loss pattern in men, with the hairline receding from the front to the back until only a horseshoe-shaped area of hair remains in the back and at the temples