A 75 year old women comes to physician because of a fever, SOB and cough that was initially dry but is now productive of reddish-brown sputum. Her temp is 38.9, HR 95, Resprate 22, BP 130/85, O2 saturation is 94 % on room air. Physical exam shows left lower lob crackles with positive fremitus. Gram stain of sputum shows a gram positive cocci. Culutures of sputum grows colonies of the organism that cause a greenish discoloration o nblood agar and are inhibited by optochin. 1. What is most likely causative organism and why?

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).