Which airways in the respiratory system are narrowed in chronic obstructive pulmonary disease or emphysema? How does this cause shortness of breath?
First thing first:
Chronic obstructive pulmonary disease (COPD) is an umbrella term, i.e. it includes a lot of conditions in which breathlessness is a symptom.
EMPHYSEMA is one disease included in COPD.
Emphysema is a condition in which the patient experiences a feeling of 'obstruction' during breathing, but actually and interestingly there is no blockage or narrowing of the respiratory tract leading to lungs in case of emphysema.
So, answer for the first part of question is, there is no narrowing of respiratory system. Now the second part of your question is answered below.
- The problem in emphysema lies within lung alveoli. Delicate partitions between alveolar sacs are damaged, creating larger air spaces by merger of alveoli but decreased surface area in lungs.
- Moreover, elasticity of lungs is gradually lost: which means during exhalation the lungs could not properly recoil, trapping more than usual volume of air (laden with carbondioxide) inside lungs for ever.
- Person with emphysema always get insufficient amount of fresh oxygenated air during inhalation. This leads to insufficient oxygen supply to blood.
- Less oxygen and more carbondioxide in blood means our autonomous nervous system increases rate of breathing (=tachypnea) but proper exchange of gases could never take place.