'A 55 yo women comes to GP. Here is what we know about her: -3 month hx chronic non productive cough. -Denies tabacco smoking (probably liar, they all are) -Admits to 10 lb weight loss in past 5 months and fatigue -Active fungal infection for past 2 years that produced cavitary lesion. -Mulstiple episodes of bacterial pneumonia Temp is 99.2, HR 72, O2 sat is 90. CXR shows ill defined 3 cm round lesion near periphery of right upper lob at previous site of her fungal infection. Scar tissue is also noted in this region. CT guided biopsy of lesion shows presence of invasive malignant cells; no evidence of fungal hyphae. 1. Whats pathology do you suspect and why? 2. What kind of lung cancer presents as a ''coin lesion'' 3. What kind of lung cancer is seen centrally and is associated with smoking? What kind of cell is it derived from?'

The main function of the respiratory system is gas exchange (O2 and CO2). Ventilation is the movement of air through the respiratory tract into (inspiration) and out of (expiration) the respiratory zone (lungs).