The __________ of the heart pumps oxygen-rich blood to the upper and lower body through the _________.

The left ventricle is responsible for pumping oxygen-rich blood that has been received from the lungs into the body. Once the blood is oxygenated, it flows from the lungs to the left atrium, then into the left ventricle. When the left ventricle contracts, it forces this oxygen-rich blood into the aorta, which is the largest artery in the body. The aorta then distributes this blood to the upper and lower body, supplying essential oxygen and nutrients to tissues and organs.

This process is critical for maintaining the body's overall function, as oxygen is vital for cellular metabolism. The left ventricle's strong muscular walls enable it to pump the blood efficiently against gravity and the pressure in the systemic circulation, making it a key component of the cardiovascular system.