It makes sense to consider the circulatory and respiratory systems together. Blood circulates the oxygen taken in by the lungs. Furthermore, keeping one healthy through exercise generally means keeping both systems healthy! This essential volume guides readers through their own body systems, taking particular care to explain the parts and processes of the heart and lungs. Age-appropriate tips for how to keep these organs strong and healthy are included throughout the text, making this an excellent addition to any health or science classroom learning.