Inspiration or inhalation is the process of bringing air from outside the body into the lungs. It is carried out by creating a pressure gradient between the lungs and the atmosphere.
When air enters the lungs, the diaphragm contracts toward the abdominal cavity, thereby increasing the space in the thoracic cavity for accommodating the inhaled air.
The volume of the thoracic chamber in the anteroposterior axis increases with the simultaneous contraction of the external intercostal muscles. This causes the ribs and the sternum to move out, thereby increasing the volume of the thoracic chamber in the dorsoventral axis.
The overall increase in the thoracic volume leads to a similar increase in the pulmonary volume. Now, as a result of this increase, the intra-pulmonary pressure becomes lesser than the atmospheric pressure. This causes the air from outside the body to move into the lungs.
List I | List II | ||
A | Expiratory capacity | I | Expiratory reserve volume + Tidal volume + Inspiratory reserve volume |
B | Functional residual capacity | II | Tidal volume + Expiratory reserve volume |
C | Vital capacity | III | Tidal volume + Inspiratory reserve volume |
D | Inspiratory capacity | IV | Expiratory reserve volume + Residual volume |
Figures 9.20(a) and (b) refer to the steady flow of a (non-viscous) liquid. Which of the two figures is incorrect ? Why ?