Aging of Respiratory System
Although the respiratory system includes the nose, throat, and trachea, it is the thorax and the lungs that undergo the major structural and functional changes of aging.
Although the respiratory system includes the nose, throat, and trachea, it is the thorax and the lungs that undergo the major structural and functional changes of aging.
The thorax, or rib cage, is formed by the sternum or breastbone, the costal cartilages which connect the ribs with the sternum or with each other, the ribs, and the bodies of the thoracic vertebrae. Although costal cartilage is normally elastic, with age it becomes rigid and may calcify. The chest diameter from anterior to increases, due to kyphosis, and a barrel-chest deformity may result.
The intercostal muscles help the diaphragm move the chest wall during respiration. These muscles fill the spaces between the ribs and connect them. With age, the intercostals atrophy and become weaker.
The lungs are composed of a porous, spongy substance. Each lung is made up of microscopic cavities called alveoli. Alveoli are covered by sacs and are clustered around the tiny tubes-alveolar ducts-that branch off from the bronchi, which bring the air to the lungs. The alveoli have fragile membranes and contain capillaries. An alveolar duct with its sacs looks like a bunch of grapes. It is estimated that there are 300 million alveoli in the lungs. The amount of surface area this adds up to is enormous. Loss of elasticity in the tissue causes the alveolar ducts and the alveoli to become strectched.
These changes in the lungs and thorax mean decreased lung expansion. When the older person takes a breath, the bases of the lungs do not inflate well and secretions that collect in the lungs are not expelled. The residual volume is the amount of air that stays in the lungs after exhalation. The older person exhales incompletely and the residual volume increases. This, in turn, reduces vital capacity, which is the largest amount of air that can be forcibly expelled following the deepest inspiration. As parts of the lung remain underventilated, the blood coming into the lungs may be poorly oxygenated. The older person is at high risk for pneumonia.
These changes in the lungs and thorax mean decreased lung expansion. When the older person takes a breath, the bases of the lungs do not inflate well and secretions that collect in the lungs are not expelled. The residual volume is the amount of air that stays in the lungs after exhalation. The older person exhales incompletely and the residual volume increases. This, in turn, reduces vital capacity, which is the largest amount of air that can be forcibly expelled following the deepest inspiration. As parts of the lung remain underventilated, the blood coming into the lungs may be poorly oxygenated. The older person is at high risk for pneumonia.
Reference :
Farrell J : Nursing Care of the Older Person, J.B. Lippincott Company, Philadelphia, 1990.
