| A | B |
|---|
| fitness | a measure of how physically well you are |
| muscles | tissues that are attached to the bones of the skeleton; contract to help us move |
| contraction | the shortening of muscles; this causes movement |
| respiration | chemical reaction in cells in which glucose is broken down into carbon dioxide and water; this process releases energy |
| alveoli (plural) / alveolus (singular) | tiny air sacs in the lungs where gas exchange takes place |
| gas exchange | a process in which one gas enters a tissue and another leaves at the same time |
| breathing | the action of drawing fresh air into the lungs and pushing stale air out of the lungs |
| inhale* | to breathe in air |
| exhale* | to breathe out air |
| intercostal muscles* | muscles between the ribs |
| diaphragm* | the action of bringing fresh air into the lungs and pushing stale air out of the lungs |
