Final answer:
During an acute asthma attack, the airways become narrowed, increasing resistance to airflow and leading to an increased residual volume.
Step-by-step explanation:
The residual volume is the amount of air that remains in the lungs after a maximal exhalation. It is the only lung volume that cannot be directly measured and can only be calculated.
The residual volume is important for preventing the lung tissues from sticking together and for maintaining a constant level of respiratory gases, such as oxygen and carbon dioxide.
During exercise, the residual volume remains the same because the lung's ability to exhale completely is not affected.
However, during an acute asthma attack, the airways become narrowed due to inflammation and constriction of the smooth muscles in the bronchioles. This narrowing leads to increased resistance to airflow, making it harder to fully exhale and resulting in an increased residual volume.
An inhaler works by delivering medication, typically a bronchodilator, directly to the airways.
This medication relaxes the smooth muscles, reducing the constriction and inflammation in the airways, which helps to open them up and decrease resistance to airflow. By reducing resistance, the inhaler allows for easier and more complete exhalation, thus decreasing the residual volume.