Emphysema is a condition characterized by abnormal permanent enlargement of the airspaces in the lungs. It can be caused by an imbalance between proteases that break down lung tissue and antiproteases that inhibit them, allowing proteases like elastase to dominate and destroy alveolar walls. Alternatively, it may be due to an imbalance between oxidants from cigarette smoke and antioxidants in the lungs, as smoke depletes antioxidants, increases oxidative stress, and damages lung tissue. The document goes on to provide more details on the protease-antiprotease and oxidant-antioxidant pathways of emphysema development.

2. Contents
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 Introduction of emphysema
 Pathogenesis
• Protease- antiprotease
mechanism
• Oxidant-antioxidant
mechanism

3. Introduction
Emphysema is a condition of a lung characterized by
abnormal permanent enlargement of the airspaces
distal to the terminal bronchioles , accompanied by
destruction of their walls and without obvious
fibrosis.
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Centriacinar or
centrilobular emphysema
affects proximal parts of
the acini i.e respiratory
bronchioles.

4. Pathogenesis
It can be explained mainly by two hypothesis:
Protease –Antiprotease Imbalance
Oxidant –Antioxidant Imbalance
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5. Protease-antiprotease imbalance
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Dominance of protease (mainly elastase) results in alveolar wall
destruction.
Protease dominates mainly due to
Genetic deficiency of protease inhibitor(mainly
α-1 antitrypsin)
Tobacco Smoking causes
I. inhibition of α-1 antitrypsin
II. increase production of elastase by neutrophils and
metalloproteinase by macrophages.

6. Oxidant-Antioxidant imbalance
Normally lung has a healthy complement of antioxidants such
as glutathione and superoxide dismutase.
Tobacco smoke has reactive oxygen species which is added by
the neutrophils and macrophages .
Depletion of lung anti –oxidant mechanism occurs.
Increased oxidative stress damages tissue resulting in
emphysema.
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8. References
Kumar Abbas Aster -Robbins Basic Pathology
Harsh Mohan –Textbook of Pathology
www.google.com
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9. Thank you
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