Classify respiratory tract diseases, their causes, and the patte

Classify respiratory tract diseases, their causes, and the pattern of associated symptoms. How are infections of upper respiratory tract different from those of lower respiratory tract? Why are infections of the upper respiratory tract milder as compared to those pertaining to the lower respiratory tract? Describe the curative methods for each of upper and lower respiratory tract infections. What are three specific factors of the immune system that help to clear the lower lung of infectious agents?