Final answer:
The heart pumps blood through three divisions of the circulatory system: coronary, pulmonary, and systemic.
Step-by-step explanation:
The heart is a complex muscle that pumps blood through the three divisions of the circulatory system: the coronary (vessels that serve the heart), pulmonary (heart and lungs), and systemic (systems of the body).
1. The simplest system would be the coronary circulation, which takes blood directly from the main artery (aorta) coming from the heart.
2. The next system in complexity would be the pulmonary circulation, where the heart pumps blood to the lungs for oxygenation.
3. The most complex system is the systemic circulation, where the heart pumps oxygenated blood to the rest of the body through a network of arteries, capillaries, and veins.