101 Facts About Ageing #28: How Age Affects The Lungs

As Daniel Patrick Moynihan, an American sociologist, politician, and diplomat once said: “Everyone is entitled to his own opinion, but not his own facts”. And we wholeheartedly agree. A shared set of facts is the first step to building a better world with longevity for all. In that spirit, we are creating a series that covers 101 indisputable facts about ageing, health and longevity.

The lungs are dependant on their elasticity to function correctly, allowing them to expand and fill with air during each inspiration before returning to their original state upon expiration. With age, the elasticity of the lungs decreases and the chest wall becomes more stiff, meaning that the respiratory muscles must generate more negative pressure in order to produce a given change in lung volume (and hence, to move a given volume of air into or out of the lungs). This means that in older individuals, respiratory muscles must work harder to deliver/expel the same amount of oxygen/carbon dioxide to and from the alveoli, where exchange between the air and the blood occurs. It also means that the volume of the lungs when respiratory muscles are relaxed or following a complete, forced exhalation (the residual volume) is greater in older individuals. This is a bad thing as it means that less volume is available for inspiration. These changes are represented in the graph below.

Calcification of the cartilage, osteoporosis, and weakening of the respiratory muscles also reduce the ribcage’s ability to expand and contract with age. Thus, not only does it take more negative pressure to expand the lungs, but the respiratory apparatus also becomes less able to generate said pressure.

The presence of antioxidants within alveoli decreases with age, while persistent inflammation within the lung increases. This can injure the alveoli, causing gas exchange to become less efficient. The result of these changes is a reduction in overall lung function and exercise capacity. Older lungs have a lower maximum rate of oxygen exchange and cannot expel air as quickly.