What does pulmonary circulation involve?

Pulmonary circulation is a crucial part of the cardiovascular system that specifically refers to the pathway of blood flow between the heart and the lungs. This process begins when deoxygenated blood is pumped from the right side of the heart through the pulmonary arteries to the lungs, where it undergoes oxygenation. In the lungs, carbon dioxide is exchanged for oxygen in the alveoli. Once this gas exchange occurs, the oxygen-rich blood is then returned to the left side of the heart via the pulmonary veins. This pathway is essential for replenishing the oxygen supply in the blood, which is vital for sustaining body functions.

The other options do not accurately describe pulmonary circulation; for instance, the flow of blood from the heart to the body corresponds to systemic circulation, and flow within the heart only does not encompass the broader aspect of circulation involving the lungs. Similarly, the mention of oxygenated blood alone ignores the initial phase of pulmonary circulation where deoxygenated blood is transported to the lungs.