Respiratory Volumes

You can see the diagram of these on page 461 of your textbook!

Respiratory therapists and other medical professional can utilize several different volumetric measurements to help determine the health of your lungs. These measurements are call respiratory volumes, and include the following:

(1) Tidal Volume-the NORMAL volume (amount) of air you breathe in/out during a NORMAL inhalation and exhalation. For an average adult, this is about 500 cc.

(2) Expiratory Reserve Volume- the volume of are that you can exhale beyond your normal exhalation. This must be forcibly exhaled. Avg. adult male = 1100 cc.

(3) Inspiratory Reserve Volume- the volume of air you can forcibly inhale beyond your normal inhalation. Avg. adult male = 3000 cc.

(4) Residual Volume-the volume of air that is ALWAYS in your lungs. It helps maintain pressure and prevent lung collapse. Avg. adult male = 1200 cc.

(5) Inspiratory Capacity- the total amount of air you are able to breathe in (inhale).

(6) Vital Capacity= Tidal Volume + Expiratory Reserve Volume + Inspiratory Reserve Volume. Avg. adult male = 4600 cc.

(7) Total Lung Capacity-total amount of air possible in your lungs.

(8) Functional Residual Capacity- the amount of air still in your lungs after a normal exhalation.

Movement of air into the lungs actually takes two (2) breaths because the air needs to be pushed from the nasal conchae (where it is swirling and warming up) into the lungs. The nasal conchae and some other spaces as well, do not have any gas exchange occuring within them. Due to this lack of exchange, these spaces are called Dead Space.

Measuring Dead Space:

• Anatomical Dead Space: the amount of air in the passageways to the lungs. This is approximately 150-mL.
• Alveolar Dead Space: Normal alveoli have gas exhange occuring within them. Alveolar dead space is when alveoli are blocked or damaged so that they cannot perform gas exchange processes.
• Total Dead Space=Anatomical Dead Space + Alveolar Dead Space.