The document discusses the circulatory and excretory systems. It describes how blood circulates through the heart, blood vessels and back to the heart in two circuits. Nutrients and oxygen are delivered and waste is removed via this circulation. The lymphatic system works alongside the circulatory system. The kidneys and urinary system make up the excretory system which removes waste from the blood through the nephrons and urine. Maintaining a balanced diet, exercise and avoiding stress helps keep these systems functioning properly.