Emphysema |
What Causes Emphysema? |
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Generally,
lungs become damaged because of reactions to irritants entering the
airways and alveoli. Researchers continue to investigate the factors
that may make some people more susceptible to emphysema than others.
But there are some clear causes for emphysema: |
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Cigarette smoking |
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Alpha-1 antitrypsin deficiency |
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Cigarette
smoking is the major cause of emphysema. When exposed to cigarette
smoke, the air sacs of the lungs produce defensive cells, called
macrophages, which "eat" the inhaled particles. But macrophages
are stimulated to release materials, which can destroy the proteins
that let the lungs expand and contract, called elastin and collagen |
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Elastin: A fibrous protein that is the major constituent of the yellow elastic fibres of connective tissue. It is rich in glycine, alanine, proline, and other nonpolar amino acids that are cross-linked, making the protein relatively insoluble. Elastic fibres can stretch to several times their length and then return to their original size. Elastin is particularly abundant in elastic cartilage, blood-vessel walls, ligaments, and the heart.
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Collagen: A fibrous structural protein that constitutes the protein of the white fibres (collagenous fibres) of skin, tendon, bone cartilage and all other connective tissues. It also occurs dispersed in a gel to provide stiffening, as in the vitreous humour of the eye. It is made of monomers of tropocollagen. Different types of collagen (types I, II, III, IV and V and others) occur in different locations and have differing chemical compositions and physical characteristics. |
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Cigarette
smoke also damages the cilia, tiny hair-like projections in the bronchi
that "sweep" foreign bodies and bacteria out of the lungs. |
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Alpha-1 Antitrypsin Deficiency |
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People who
a deficiency of a protein called alpha-1 antitrypsin (AAT) are at
a higher risk of developing severe emphysema. Alpha-1 antitrypsin
deficiency (AAT deficiency) is an inherited condition and occurs
in varying degrees. AAT is thought to protect against some of the
damage caused by macrophages. In AAT deficiency-related emphysema,
the walls of the bronchial tubes and the alveoli are both damaged,
often leading to severe disease. |
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Peter Scott - Team Leader
