If you're seeing this message, it means we're having trouble loading external resources for Khan Academy.
If you're behind a web filter, please make sure that the domains
*.kastatic.org and *.kasandbox.org are unblocked.
Learn what the main classifications of lung diseases are: obstructive, restrictive, ventilation, and perfusion. Discover the classification of common diseases like asthma, emphysema, and pneumonia.
How can you tell someone is having troubles breathing? Increased work of breathing, the feeling of shortness of breath, and cyanosis are all common symptoms of respiratory distress. Learn what these symptoms look like and why they occur.
Why do we need a new flu vaccine every year? Learn about the pneumonia and flu vaccines and how they help your body fight off infection.