Major Lung Volumes and Capacities Help

Introduction Major Lung Volumes and Capacities

This section now reveals how much we breathe. Specifically, this section deals with various lung volumes and capacities .

Tidal Volume (tv)

Take a single breath while you are resting. This breath is called the tidal volume, abbreviated as TV. The tidal volume (TV) is named for its resemblance to a real tide – the moving of waves of water back-and-forth, back-and-forth, back-and-forth, upon the sand of a beach. The tidal volume is the amount of air exhaled after the person takes a normal resting inspiration. It amounts to about 500 ml (milliliters) in an average human adult.

Vital Capacity (vc)

Another important measurement of pulmonary function is the vital capacity, abbreviated as VC. Vita ( VEE -tah) comes from the Latin and means “life.” The vital capacity (VC) therefore represents a person’s capacity for life. Technically, the VC is defined as the total amount of air that a person can inhale and exhale from normal, uncollapsed lungs.

Residual Volume (rv)

When you or I exhale, our alveoli normally don’t completely collapse. If we picture each alveolus as a balloon, then the alveolus balloon only partially deflates during expiration, simply becoming smaller, rather than totally deflating. As a result, there is usually a residual volume, or RV . The residual volume (RV) is literally the residual or “left-over” volume, still remaining within the alveoli even after expiration has occurred. This partial, residual inflation greatly reduces the amount of work required to completely re-inflate the lungs during the next cycle of inspiration.

Total Lung Capacity (tlc)

If we add both the vital capacity (VC) and the residual volume (RV) together, we obtain the total lung capacity (TLC) :

The total lung capacity therefore represents the total amount of air that the lungs can possibly hold.

Practice problems for these concepts can be found at:  The Respiratory System Test