Take a deep breath as Dr. Know looks at how the respiratory system works. First he bellies up to the oxygen bar to find out if there's any health benefit to breathing pure oxygen. Then, stay awake as he tries to determine whether yawning really is contagious.
Take a deep breath as Dr. Know looks at how the respiratory system works. First he bellies up to the oxygen bar to find out if there's any health benefit to breathing pure oxygen. Then, stay awake as he tries to determine whether yawning really is contagious.
