- changes depending on amount of carbon dioxide in your blood - more carbon dioxide, breathing rate increases

- a muscle beneath your lungs that contracts and relaxes to help move gases into and out of your lungs

- breathing air in - lungs expand and chest rises - diaphragm contracts - breathing out carbon dioxide and wastes - lungs relax and chest falls - Diaphragm relaxes

- air enters lungs containing oxygen - air passes from lungs to circulatory system (blood) - blood carries oxygen and digestive system supplies glucose to same cells - oxygen from cells releases energy from glucose - carbon dioxide and water are waste products - wastes are carried back to lungs by blood and are exhaled back out

- Lung cancer- 23 times higher risk for males and 11 times higher risk for females - Chronic Bronchitis and Emphysema- 5 times higher risk - Heart Disease- 2 times higher risk - chemicals in tobacco are poisons and destroy cells - high temperatures, smoke, and carbon monoxide can injure cells - secondhand smoke- inhaling smoke from others that are smoking, also unhealthy and can harm the respiratory system

- Smoking - Polluted air - Coal dust - asbestos

- Caused by bacteria, viruses or other micro- organisms - usually affects upper respiratory system- from nose to pharynx - can cause irritation and swelling in larynx, trachea, and bronchi

- Caused by a virus - can affect many body systems - virus multiplies in the cells of the alveoli and damages them

- Infection in the alveoli - can be caused by bacteria, viruses, or other micro-organisms - can be treated with antibiotics

- Bronchial tubes are irritated and swell, and too much mucus is produced - bronchitis can be treated with antibiotics and clears up within a few weeks, if not it is called chronic bronchitis - person coughs a lot to clear mucus from airway, but it damages cilia and bronchial tubes and scar tissue can form and the respiratory system cannot perform properly

- Disease that causes alveoli in the lungs to enlarge - when cells in alveoli swell, they release an enzyme that causes walls of alveoli to break down - causes less oxygen in the bloodstream and shortness of breath - often develop heart problems because heart has to work harder to supply oxygen to body cells

- 3 rd leading cause of death in U.S. - greatest cause is inhaling tar in cigarette smoke - carcinogens- substances that can cause uncontrolled growth of cells

- Lung disorder that can cause shortness of breath, wheezing, or coughing - asthma attack- bronchial tubes contract quickly, medicines in inhalers relax the tubes - often an allergic reaction to a foreign substance - attacks can be caused by cigarette smoke, plant pollen, certain foods, or stress