What is Emphysema?
Emphysema is a serious lung condition in which the small air sacs (or air spaces) in the lungs are affected.
The primary function of the lungs is to exchange gas, between air and the bloodstream, and this is done in the 300 million thin- walled, distensible sacs (called alveoli) in the lungs. From the trachea (the windpipe) to the alveoli are many divisions of air passages that get smaller and smaller, (the bronchi and bronchioles) and it is only the final centimetre (in the respiratory bronchioles, alveolar ducts and alveoli) that oxygen (O2) is passed into the blood, and carbon dioxide (CO2) is passed out.
Emphysema is defined (histo-pathologically), as the irreversible dilatation of air spaces, caused by destruction of their walls.
It is caused by loss of elasticity of the lung tissue, both of the airways and the tiny air sacs, (alveoli), and the walls between many of the air sacs are gradually destroyed. This results in permanent “holes” in the lung tissue. Because the structure of the tiny airways is lost, the ability of the lungs to get rid of CO2 and absorb O2 efficiently is lost. Thus, less O2 is able to get into the blood, and to vital organs, and less CO2 can be got rid of, causing a rise in blood levels of the latter.
Also, the small airways collapse, during expiration (breathing out), instead of remaining open, thus causing air to be trapped in the lungs. This is because the natural elasticity of the lungs [which enables the airways to stay open] is reduced, and because there is destruction of the alveolar wall attachments, which normally hold the walls of the small airways open.
The lungs become over inflated because of this difficulty in breathing out, and this is obvious in emphysema sufferers, in an increased diameter of the chest antero - posteriorly (front to back), relative to the lateral (side to side) diameter.
A bulla is a locally over-distended area of emphysema. It is a thin- walled airspace caused by alveolar wall rupture. They may be any size, and may exist alone or in a collection. Rupture of a bulla may cause a pneumothorax, (a sudden collection of air in the chest cavity, associated with collapse of one lung).
COPD is the term encompassing chronic bronchitis and emphysema. In most people, there is considerable overlap in the two conditions although each condition may exist by itself. COPD does not include other obstructive lung diseases such as asthma.
