A systemic circuit refers to the pathway through which oxygenated blood flows from the heart to the rest of the body and back. It begins when the left ventricle of the heart pumps blood into the aorta, the largest artery. This blood travels through various arteries and capillaries, delivering oxygen and nutrients to tissues and organs. After the exchange of gases and nutrients, deoxygenated blood returns to the heart through veins. It enters the right atrium, completing the circuit. This process is essential for maintaining the body's overall health and function, ensuring that all cells receive the necessary resources to operate effectively.