Final answer:
The left ventricle is the main pumping chamber for the systemic circuit, ejecting blood into the aorta via the aortic semilunar valve, which prevents backflow.
Step-by-step explanation:
The left ventricle is the major pumping chamber for the systemic circuit; it ejects blood into the aorta through the aortic semilunar valve. The systemic circuit refers to the part of the circulatory system that carries oxygenated blood from the heart to the body and returns deoxygenated blood back to the heart. The aortic semilunar valve, also known as the aortic valve, plays a crucial role in preventing the backflow of blood from the aorta into the left ventricle. When the left ventricle contracts, blood is forced into the aorta, and as the heart relaxes, the valve closes to maintain unidirectional blood flow and proper circulation throughout the body.