Emphysema

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Emphysema is a form of Chronic obstructive pulmonary disorder (COPD). The disease has two forms; familial and non-familial. Familial emphysema is a result of a Genetic mutation of a common respiratory protein Alpha-1-antitrypsin (AAT) which protects tissues from Enzymes of inflammatory response. For patients with a lack of AAT protein, the enzyme which is normally kept regulated in check, is allowed to attack the lungs – a form of autoimmune response. Non-familial emphysema is more common and is generally caused by smoking, in fact between 80% and 90% of all cases of emphysema are caused by smoking. When smoking, particles of Carbon monoxide enter the lungs and irritate the Alveoli causing large amounts of damage.

Alveoli are small spherical sacs of epithelial cells (one cell thick) that allow for efficient gas exchange into the bloodstream. They are extremely compact which allows 300 million of each alveolus to fit into each lung, resulting in an enormous surface area – the key to the efficiency of gaseous exchange in the lungs. Alveoli expand in size when the air is inhaled and recoil during exhalation, this process is enabled by the protein elastin.

In emphysematous lungs, there is a much larger concentration of carbon monoxide (due to smoking) which in turn leads to an increased production of the enzyme elastase, which breaks down elastin. Without this key protein, the alveoli become permanently stretched leaving the lungs unable to expel all of the air during exhalation. Each alveolus also becomes more susceptible to tearing and therefore scar tissue forms. This scar tissue results in a smaller surface area for gas exchange making the process far less efficient.

There are several typical symptoms associated with this disease which include:

References

  1. Toole, G., Toole, S., 2008. AQA Biology, Cheltenham: Nelson Thornes
  2. Cleveland Clinic. (2011) Emphysema. Available at: http://my.clevelandclinic.org/health/diseases_conditions/hic-emphysema (last accessed 26/11/2014)
  3. Patient.co.uk (2012) Alpha-1-Antitrypsin Deficiency. Available at: http://www.patient.co.uk/health/alpha-1-antitrypsin-deficiency-leaflet (last accessed 26/11/2014)
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