Final answer:
The heart pumps oxygen-rich blood that hemoglobin in red blood cells carries to tissues throughout the body, particularly after picking up oxygen in the lungs.
Step-by-step explanation:
When we look at how blood is pumped around the body, we focus on how hemoglobin within the red blood cells attaches to oxygen in the lungs and how carbon dioxide is transported back to the lungs to be exchanged for oxygen. After blood is oxygenated in the lungs, the heart pumps this oxygen-rich blood to the rest of the body. The answer to the question would be tissues, as the heart pumps blood to tissues through the arteries which then reaches the capillaries where gas exchange occurs, supplying the tissues with oxygen and removing carbon dioxide.