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, which 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 small airways, finally filling tiny sacs called alveoli. Blood circulates around the alveoli through capillaries. 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.

The lungs are continuously being exposed to particles in the air, including smoke, pollen, dust, and microorganisms. Therefore, another major function of the lungs is to protect from any diseases that may be caused by inhaled particles.

AGING CHANGES

An average person continues to slowly make new alveoli until about age 20. After this age, 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 due to various factors including the loss of a tissue protein called elastin.

Changes in the bones and muscles result in a slightly increased front-to-back chest diameter. Loss of bone mass in the ribs and vertebrae, and mineral deposits in the rib cartilage, change the spine curvature. There may be front-to-back curvature (kyphosis or lordosis) or side-to-side curvature (scoliosis).

The maximal force one can generate on inspiration (breathing in) or expiration (breathing out) 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 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 one is able to achieve on inspiration and expiration decreases. Usual breathing should remain adequate, and even a very old person should, under most circumstances, be able to breathe without effort.