Answer:
The heart's Lower chambers
Step-by-step explanation:
The heart's ventricles are the heart's lower chambers. The heart has four chambers, with the two ventricles located at the bottom of the heart and the two atria (upper chambers) located at the top. The ventricles are responsible for pumping blood out of the heart and into the circulatory system, while the atria receive blood returning to the heart from the rest of the body. The ventricles have thicker walls than the atria, as they need to generate greater pressure to push blood through the circulatory system.