[ Post a Response | The Sublime Desire of Cigarette Smoking ]
Posted by M G F on July 28, 2007, 3:25 pm, in reply to "Progression of Lung Discoloration?" Patients with extremely sever emphysema are occasionally treated with upper lobe lung reduction surgery in which the most severely damaged tissue is removed. By reducing lung volume, less pressure is put on the diaphragm so that it can operate more easily. You are correct that sitting and smoking does result in a higher concentration in the upper lobes because full expansion is restricted. As an exercise to demonstrate how your lungs inflate, try breathing from your diaphragm with your hand on your stomach while sitting, prone, standing, and bending over. Isn't breathing Fun!?!?
From the tratachia, the sequence is primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, alveoli. The tertiary bronchi are all roughly the same length as are the secondary bronchi which branch off at different points along the primary bronchi. You are correct that being the same length helps maintain the air pressure necessary to keep our lungs inflated. In normal respiration, most breaths fill the secondary bronchi closest to the trachea first. When inhaling smoke, the deeper the inhale, the more diluted the smoke becomes as it travels along the bronchial tree. As a general rule, the alveoli closest to the trachea begin to loose elasticity and their ability to expel air or smoke before those further down the line because they have received the highest concentration of tar. As a result, the secondary bronchi and their alveoli further down the line begin to inflate before those closest to the trachea resulting in more even distribution of the pollutants. Keep in mind that these changes are gradual and take place over an extended period of time. As they occur, the smoker unconsciously changes the way she breaths in subtle ways, taking deeper breaths and using her diaphragm more to draw the air or smoke deeper into her lungs into those areas with greater elasticity (and ability to absorb oxygen) Over time, the uppermost alveoli become chronically inflated or hyper-inflated and press on the smoker's sternum giving her a rounded or "barrel" chest. Even though this change usually occurs only after many, many years of smoking, measurable loss of elasticity in the uppermost alveoli is common after as few as 18 pack years.
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