What are the two main circuits of the cardiovascular system?

The cardiovascular system is primarily divided into two main circuits: the systemic circuit and the pulmonary circuit.

The systemic circuit is responsible for transporting oxygenated blood from the left side of the heart to the rest of the body, where oxygen and nutrients are delivered to tissues, and carbon dioxide and waste products are collected. Blood then returns to the right side of the heart. This circuit is crucial for maintaining the oxygen supply needed for cellular metabolism throughout the body.

The pulmonary circuit, on the other hand, is responsible for transporting deoxygenated blood from the right side of the heart to the lungs. In the lungs, carbon dioxide is exchanged for oxygen, resulting in oxygenated blood that then returns to the left side of the heart, ready to be pumped into the systemic circuit. This exchange is vital for replenishing the blood's oxygen content and removing carbon dioxide.

Other options listed involve circuits that are either subsets of the broader systemic or pulmonary circuits or that serve different functions, such as nutrient delivery and waste management without being part of the fundamental circulation scheme needed for gas exchange and systemic oxygen delivery.