Video "Lung Function"

### 4 volumes:
- Tidal volume: 500-750ml and is the amount of air normally breathed in and out
- Inspiratory reserve volume: The difference in the total volume of air inspired with maximum inspiratory effort compared to the tidal volume. Typically about 3L.
- Expiratory reserve volume: The amount of air that can be exhaled in addition to the tidal volume. Typically about 1.5L.
- Residual volume: The amount of air remaining in the lungs after maximum expiratory effort. Typically about 1L.

### Lung capacities:
- Total lung capacity: the sum of the four lung volumes (about 6L).

### Question:
Why can we not breathe out all the air in our lungs?