| A | B |
|---|
| respiration | The process by which cells breakdown simple food molecules to release the energy they contain |
| cilia | The hairlike projections on the outside of cells that move in a wavelike manner |
| pharynx | The throat; part of both the respiratory and digestive systems |
| trachea | The windpipe; a passage through which air moves in the respiratory system |
| lungs | The main organs of the respiratory system, where gas exchange takes place |
| alveoli | Tiny sacs of lung tissue specialized for the movement of gases between the air and the blood |
| diaphragm | A large, dome-shaped muscle that plays an important role in breathing |
| vocal cords | Folds of connective tissue that stretch across the opening of the larnyx and produce a person's voice |
| tar | A dark, sticky substance produced when tobacco burns |
| carbon dioxide | A colorless, odorless gas produced when substances-including tobacco-are burned |
| nicotine | A drug in tobacco that speeds up the activities of the nervous system, heart, and other organs of the body |
| addiction | A physical dependence on a substance; an intense need by the body for a substance |
| bronchitis | An irratation of the breathing passages in which the small passages become narrower than the normal and often clogged with mucus |
| emphysema | A serious disease that destroys lung tissue and causes difficulty in breathing |
| passive smoking | The involuntary inhalation of smoke from other people's cigarretes, cigars, or pipes |
| urea | A chemical that comes from the breakdown of proteins and is removed from the body by the kidneys |
| kidney | A major organ of the excretory system; eliminates urea, excess water, and othe waste materials from the body |
| ureter | A narrow tibe that carries urine from one of the kidneys to the bladder |
| urinary bladder | A saclike muscular organ that stores urine until it is eliminated from the body |
| urethra | A small tube through which urine flows from the body |
