residual volume

volume of air remaining in respiration passages and lungs after the most forceful expiration

expiratory reserve volume

amount of air forcefully expired after expiration of normal tidal volume.

inspiratory reserve volume

amount of air inspired forcefully after inspiration of normal tidal volume

pulmonary capacities

Inspiratory capacity: tidal volume plus inspiratory reserve volume. Functional residual capacity: expiratory reserve volume plus the residual volume. Vital capacity: sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume . Total lung capacity: sum of inspiratory and expiratory reserve volumes plus the tidal volume and residual volume.

invertebrates respiratory system

Sponges do not have speciliazed respiratory organs. Simple diffusions is enough to support all cells with oxygen. Water flows into a sponge througt side openings and out of the top opening osculum. The water current provides both food and oxygen removes waste products. All of the cells in the sponge obtain their oxygen from the circulated water. Flatwarms also do not need respiratory organs as like lungs or gills, simple diffusion occur for gas exchange.