Influence of Internal and External Forces on Lung

Mechanical forces that occur during breathing have been reported to be capable of causing failure of the ECM at loci of stress and to contribute to the progression of emphysema. Chronic asthma is associated with a marked increase in the airway wall thickness, and an increased muscle cell mass. Hyperplasia of airway smooth muscle cells in vivo is probably accompanied by a change in contractile capacity and appears to be a consequence of the increased forces required for breathing through narrowed airways. 

6 Summary of Effects of Internal and External Mechanical Forces 

To understand how mechanical energy is transduced into chemical energy within the cell requires that we understand the specific structure and composition of the ECM found in each tissue. Unfortunately, the structure and composition of each ECM is quite complex and therefore it is only possible to provide general relationships between structure and function to 

External forces applied to tissues lead to stretching of collagen, elastic fibers, and smooth muscle in the associated ECMs as well as proteoglycan deformation and fluid flow from within the matrix. The application of these forces ultimately leads to matrix remodeling and energy storage. The question arises as to how external mechanical events trigger cellular synthesis. 

Although there is some information on the effects of mechanical forces on the structure of collagen and the possible mechanism by which this is transduced at the cell membrane, very little information is available on the 

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