Aging changes in the lungs

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Changes in lung tissue with age

Respiratory cilia

The lungs have two primary functions: to acquire oxygen from the air, which is required for life, and to remove carbon dioxide from the body. Carbon dioxide is a byproduct of many of the chemical reactions that sustain life.

During breathing, air enters and exits the lungs. It flows in through increasingly smaller airways, finally filling tiny sacs called alveoli. Blood circulates around the alveoli through capillaries (tiny blood vessels). Where the capillaries and alveoli meet, oxygen crosses into the bloodstream. At the same time, carbon dioxide crosses from the bloodstream into the alveoli to be exhaled.

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The lungs are continuously being exposed to particles in the air, including smoke, pollen, dust, and microorganisms. Some of these inhaled substances can cause lung disease if enough is inhaled or if the body is particularly sensitive to them.

AGING CHANGES

People normally make new alveoli until about age 20. After that, the lungs begin to lose some of their tissue. The number of alveoli decreases, and there is a corresponding decrease in lung capillaries. The lungs also become less elastic (able to expand and contract) due to various factors including the loss of a tissue protein called elastin.

Changes in the bones and muscles increase the front-to-back size of the chest. Loss of bone mass in the ribs and spine bones (vertabrae), and mineral deposits in the rib cartilage, change the curve of the spine. There may be front-to-back curvature (kyphosis or lordosis) or side-to-side curvature (scoliosis).

The maximal force you can generate when breathing in (inspiration) or when breathing out (expiration) decreases with age, as the diaphragm and muscles between the ribs (intercostals) become weaker. The chest is less able to stretch to breathe, and the pattern of breathing may change slightly to compensate for this decreased ability to expand the chest.

EFFECT OF CHANGES

Maximum lung function decreases with age. The amount of oxygen diffusing from the air sacs into the blood decreases. The rate of air flow through the airways slowly declines after age 30. And the maximal force you can generate on inspiration and expiration decreases. However, even elderly people should have adequate lung function to carry out daily activities, because we have "extra" lung function in our youth. This is why normal people can tolerate surgical removal of an entire lung and still breathe reasonably well.