Final answer:
The normal amount of air that is displaced during regular inhalation and exhalation without extra force is called tidal volume. Tidal volume approximates about half a liter, which is under the capacity of average drink bottles. The lungs' alveoli enable passive exhalation, and residual volume is essential for lung flexibility and consistent gas concentrations.
Step-by-step explanation:
The normal amount of air displaced between inhalation and exhalation when no additional force is applied is known as tidal volume (TV). Tidal volume measures the amount of air that is inspired and expired during a normal breath, which is typically around half a liter, similar to the capacity of a 20-ounce drink bottle. The lungs contain hundreds of millions of sacs called alveoli; these structures facilitate gas exchange and allow for exhalation through the contraction of sacs via surface tension without muscle action.
The process of normal expiration is passive, relying on the elasticity of lung tissue and the relaxation of muscles such as the diaphragm and intercostal muscles. Other lung volumes include expiratory reserve volume (ERV), inspiratory reserve volume (IRV), and residual volume (RV). Residual volume is the amount of air left in the lungs after a forced exhalation and is crucial for preventing the lungs from collapsing and maintaining a consistent concentration of respiratory gases.