you could do a short story about a man who leaves his home full of energy and ready to go ( like oxinated blood leaving the hart) and the farther he walks away from is home the less energy he has. when he don with his walk he goes home to rest ( deoxinated blood going back to the hart) when he gets home he goes to his home he goes to the refrigerator and gets some food ( deoxinated blood goes to lungs) and the goes to bed to do the same thing later
