1. The passages that direct air into the lungs
Respiration
The process by which cells break down simple food molecules to release the energy they contain
Cilia
The hair like projections on the outside of cells that move in a wave like manner
Pharynx
The throat
Trachea
The windpipe, a passage through which air moves in the respiratory system
Bronchi
The passages that direct air into the lungs

2. Lungs Alveoli Diaphragm Larynx Vocal Cords
An organ found in air breathing vertebrates that exchanges oxygen and carbon dioxide in the blood
Tiny sacs of lung tissue specialized for the movement of gases between air and blood
Alveoli
Diaphragm
A large muscle located at the bottom of a mammal’s rib cage that functions in breathing
Larynx
The voice box
Vocal Cords
Folds of connective tissue that stretch across the opening of the larynx and produce a person’s voice

3. Tar Carbon Monoxide Nicotine Addiction Bronchitis
A dark sticky substance that forms when tobacco burns
Carbon Monoxide
A colorless odorless gas produced when substances including tobacco burn
Nicotine
A stimulant drug in tobacco that increases the activities of the nervous system, heart and other organs
Addiction
A physical dependence on a substance
Bronchitis
An irritation of the breathing passages in which small passages become narrower than normal and may be clogged with mucus

4. Emphysema Excretion Urea Kidney Urine
A serious disease that destroys lung tissue and causes breathing difficulties
Excretion
The process by which wastes are removed from the body
Urea
A chemical that comes from the breakdown of proteins
Kidney
A major organ of the excretory system that removes urea and other wastes from the blood
Urine
A watery fluid produced by the kidneys that contains urea and other wastes

5. A small tube through which urine flows from the body
Ureter
A narrow tube that carries urine form the kidneys to the urinary bladder
Urinary Bladder
A sac like muscular organ that stores urine until it is eliminated from the body
Urethra
A small tube through which urine flows from the body
Nephron
Small filtering structure found in the kidneys that removes waste from blood and produces urine