| A | B |
|---|
| epidermis | the outer, thinner layer of the skin that is composed of living and dead cells |
| dermis | the thicker layer ofthe skin beneath the epidermis that is made up of connective tissue and contains blood vessels and nerves |
| melanin | a pigment that gives the skin, hair, and iris of the eyes their color |
| sebaceous glands | structures within the skin that produce an oily secretion called sebum |
| sweat glands | structures withing the dermis that secete perspiration through ducts to pores on the skin's surface |
| melanoma | the most serious form of skin cancer |
| hair follicle | a structure that surrounds the root of a hair |
| dandruff | a condition that can occur if the scalp becomes too dry and dead skin cells are shed as sticky, white flakes |
| periodontium | the area immediately aroun the teeth |
| pulp | the tissue that contains the blood vessels and nerves of a tooth |
| plaque | a sticky, colorless film that acts on sugar to form acids that destroy tooth enamel and irritate gums |
| periodontal disease | an inflammation of the periodontal structures |
| tartar | hard, crustlike substance formed when plaque hardens |
| lacrimal gland | the gland that secretes tears into ducts that empty into the eye |
| sclera | the tough, white part of the eye |
| cornea | a transparent tissue that bends and focuses light before it enters the lens |
| choroid | a thin structure that lines the inside of the sclera |
| retina | the light-sensitive membrane on whichimages ae cast by the cornea |
| external auditory canal | a passageway about one inch long that leads to the remaining portion of the outer ear, the eardrum |
| auditory ossicles | three small bones linked together that connect the eardrum to the inner ear |
| labyrinth | the inner ear which consists of a network of curved and spiral passages with three main parts |
| tinnitus | a condition in which a ringing, buzzing, whistling, roaring, hissing, or other sound s heard in the ear in the absence of external sound |
