| A | B |
|---|
| Heart | muscular, four-chambered pump that circulates blood |
| Nose | warms and filters the air |
| Veins | thin-walled vessels that return blood to the heart |
| Heart valves | ensure one-way movement of blood |
| Trachea | cartilage-banded air passageway that is covered by the epiglottis transporting air to the bronchi |
| Capillaries | small vessels that connect arteries and veins |
| Bronchi | branching tubes that connect the lungs to the trachea |
| Alveoli | grape-like structures where the exchange of carbon dioxide and oxygen take place |
| Diaphragm | powerful muscle that controls breathing |
| Arteries | thick, muscular-walled vessels that move blood away from the heart |
