Lung Volumes & Lung Capacity.

[9/1, 20:20] pillairohit1991: One good way to remember this:

Take a deep breath in upto your maximum capacity. Now there is approximately 6 litres of air in your lungs. That is your Total lung capacity.

 Now breathe out as deep as you can. You just breathed out 4800 mls of air. That is your vital Capacity.

 But even after breathing out completely, 1200 mls of air is still reserve in your lungs. That is your residual volume.

 Now breathe normally. In your normal breathing, approximately 500 mls of air is going in and out. That is your tidal volume.

 Now breathe normally like in tidal Volume. Now after a normal tidal volume inhalation happens breathe in effortfully to your maximum capacity. You just breathed in 3200 mls of air over your tidal volume. That is your Inspiratory Reserve Volume.

 So basically your Tidal Volume was already 500 mls. On the top of that you further breathed in 3200 mls. So that becomes a total of 3700 mls which is your actual Inspiratory capacity.

 Now breathe normally like in tidal volume. Now after your normal tidal volume exhalation, exhale further to the best  of your capacity. In this forceful exhalation you were able to exhale approximately 1100 mls of air. This 1100 mls of your forcefully exhaled air is your Expiratory Reserve Volume. Basically how much you can further exhale after a natural exhalation.

 But Remember, no matter how much ever strongly you exhale, for an average individual there is always a Residual Volume of 1200 mls pending in their lungs.

 Now Breathe normally as in tidal volume. As we mentioned earlier, in tidal volume there is only 500 mls of air going in or out . So if you do a forceful exhalation, as mentioned before, still 1200 mls of air is residual in your lungs. But let's say , you don't do forceful exhalation. After a normal tidal volume exhalation the amount of Air pending in your lungs now is basically Residual Volume (1200 mls) + Expiratory Reserve Volume (1100 ml)= 2300 ml. This 2300 ml is called your Functional Reserve Capacity. Basically, Functional Reserve Capacity is the volume of air remaining in your lungs after a natural exhalation.