Lung Volume and Capacities
There are various lung volumes and capacities. According to Hasleton, Flieder & Spencer (2013), lung volumes include Total Volume, Inspiratory Reserve Volume (IRV), Expiratory Reserve Volume (ERV) and the residual volume (RV). On the other hand, there are four lung capacities. They include total lung capacity (TLC), Vital Capacity (VC), Functional Residual Capacity (FRC) and the Inspiratory capacity (IC). Lung capacities are the sub- divisions of the total volume that may include two or more of the primary lung volumes. The lung capacity and volumes are often measured in millimeters (mL).
Residual Volume (RV) is defined as the volume of air that remains in the lungs after a maximal expiration. Human lungs work like a balloon that is inflated and deflated on occasions. When individual forces all the air in the balloon, there is the little that will remain. The tiny amount of air is the residual volume. Likewise, the residual volume is the amount of air that remains when an individual exhales maximally. The residual volume is often 1200 mL. Functional Reserve Capacity (FRC) is the amount of air that often remains in the human lungs after a normal expiration. Often it is the sum of Residual Volume and the expiratory reserve volume. Typically, it is 2400 millimeters (Widmaier, et al. 2011). The Inspiratory Reserve Volume (IRV) is the additional amount of air that can be forcibly inhaled after a normal inspiration. It is often 3100 mL on the other hand Expiratory Reserve Volume is the additional amount of air that can be forcibly exhaled after a normal exhalation. The normal expiratory reserve volume is 1200 mL (Main & Denehy, 2015). Total lung capacity is the maximum amount of air that can occupy the human lungs. Total lung capacity may also be defined as the sum of total volume, inspiratory reserve volume, expiratory reserve volume and the reserve volume. The total lung capacity is often 6, 000 mL.
There are various diseases that affect the amount of air that remains in the human lungs after maximal expiration. According to Hasleton, Flieder & Spencer (2013), these diseases include Chronic Obstructive Pulmonary Diseases that is a combination of emphysema and chronic bronchitis. Others include Asthma, Bronchiectasis, bronchiolitis and cystic fibrosis. These diseases fall into the category of obstructive lung diseases. They make a patient experience difficulty expelling all the air from the lungs. Bronchiolitis is the inflammation of the bronchi. When the bronchi are inflamed, it results in the narrowing and the blockage of the airways. Therefore, the patient experiences difficulty in exhaling the air leading to increasing of air that remains in the human lungs. The other disorder is the bronchiectasis. It is a failure to the function of the bronchi activity. Therefore, there is the increase of air that gets trapped in the lungs leading to the increase in the residual volume.
Finally, Asthma is another obstructive lung disorder. Asthma is the generalized inflammation of the airways as the result of an allergic reaction. The airways are often narrowed and blocked. The Inflammation of the airways and further blockage lead to the decreased ability of exhalation. The patient experiences difficulty to completely rid the lungs of air. Hence, the amount of air that remains in the lungs after full expiration is increased. The air gets trapped in the lungs hence causing hyperventilation.
Hasleton, P. S., Flieder, D. B., & Spencer, H. (2013). Spencer’s pathology of the lung. Cambridge: Cambridge University Press.
Main, E., & Denehy, L. (2015). Cardiorespiratory Physiotherapy: Formerly Physiotherapy for Respiratory and Cardiac Problems. Saintt Louis: Elsevier Health Sciences UK.
Widmaier, E. P., Raff, H., Strang, K. T., & Vander, A. J. (2011). Vander’s human physiology: The mechanisms of body function. New York: McGraw-Hill.