lungs are the focal point of the respiratory system, which also includes the respiratory tract, the channel by which air flows into and out of the lungs.
(lungs; are; the focal point of the respiratory system) (the respiratory system; includes; the respiratory tract) (air; flows; into and out of the lungs; L:the channel)
lungs the respiratory system air
are includes flows
the focal point of the respiratory system
the respiratory tract
into and out of the lungs L:the channel