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Student at Alfred University. This page is for a class project and will have information and a topic up soon.

Spirometry is used to measure lung function. The total lung capacity(TLC), functional residual capacity (FRC), residual volume (RV), and vital capacity (VC) are all values that can be tested using this method. Spirometry is used to help detect, but not diagnose, respiratory issues like COPD, and asthma. It is a simple, and cost effective screening method.[1] Further evaluation of a person's respiratory function can be done by assessing the minute ventilation, forced vital capacity (FVC), and forced expiratory volume (FEV). These values differ in men and women this is because of men tending to be larger than women.

TLC is the maximum amount of air in the lungs after maximum inhalation. In men the average TLC is 6000 ml, and in women it is 4200 ml. FRC is the amount of air left in the lungs after normal exhalation. Men average around 2400 ml left, women retain around 1800 ml. RV is amount of air left in the lungs after a forced exhalation. The average RV in men is 1200 ml and women 1100 ml. VC is the maximum amount of air that can be exhaled after a maximum inhalation. Men tend to average 4800 ml and women 3100 ml.


Exhalation takes longer then inhalation since it is believed to facilitate better exchange of gases. Parts of the nervous system help to regulate respiration in humans. The exhaled air isn’t just carbon dioxide; it contains a mixture of other gases. Human breath contains volatile organic compounds (VOCs). These compounds consist of methanol, isoprene, acetone, ethanol and other alcohols. The exhaled mixture also contains keytones, water and other hydrocarbons.[2]


Yawning is considered a nonrespiratoy gas movement. A nonrespiratory gas movement are other processes that move air in and out of the lungs that don't include breathing. Yawning is a reflex that tends to disrupt the normal breathing rhythm and is believed to be contagious as well.[3] The reason why we yawn is unknown, but some think we yawn as a way to regulate the body’s levels of O2 and CO2. Studies done in a controlled environment with different levels of O2 and CO2 have disproved that hypothesis. Although there isn’t a concrete explanation as to why we yawn, other’s think people exhale as a cooling mechanism for our brains. Studies on animals have supported this idea and it is possible humans could be linked to it as well.[4] What is known is that yawning does ventilate all the alveoli in the lungs.


  1. ^ Kivastik, J (2001). "Spirometric reference values in estonian school children". Clinical Physiology. 21 (4): 490–497. doi:10.1046/j.1365-2281.2001.00352.x. PMID 11442581. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  2. ^ Fenske, J.D. (1999). "Human breath emissions of VOCs". Journal of Air & Waste Management Association. 49 (5): 594–598. doi:10.1080/10473289.1999.10463831. PMID 10352577. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  3. ^ Sarnecki, John (2008). "Content and Contagion in Yawning". Philosophical Psychology. 21 (6): 721–737. doi:10.1080/09515080802513292.
  4. ^ Corey, T.P. (2011). "Changes in physiology before, during, and after yawning". Frontiers in Evolutionary Neuroscience. 3 (7): 1–11. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)