Final answer:
Increased O2 supply improves cardiac output and reduces workload on the heart by increasing the heart's efficiency and reducing resistance to blood flow.
Step-by-step explanation:
Increased O2 supply improves cardiac output by increasing the oxygen available to the heart muscle. This allows the heart to contract with greater strength, resulting in an increased stroke volume. When more oxygen is delivered to the heart, it can work more efficiently and pump a greater volume of blood with each beat. This helps to reduce the workload on the heart by improving its efficiency.
For example, during exercise, the demand for oxygen increases as muscles require more energy. An increased supply of oxygen allows the heart to meet this demand by pumping more blood.
Additionally, oxygen-rich blood also helps to relax the blood vessels, increasing their diameter. This reduces resistance to blood flow and lowers blood pressure, further reducing the workload on the heart.