Final answer:
The ventricles are larger than the atria, with the ventricles having thicker and more muscular walls to pump blood under higher pressure, especially the left ventricle for systemic circulation.
Step-by-step explanation:
The student's question pertains to the comparison between the ventricles and the atria of the heart. Looking at the anatomy of the heart, we learn that an atrium (singular for atria) is one of the two smaller, thin-walled chambers located at the top part of the heart. Conversely, a ventricle is one of the two larger, muscular V-shaped chambers that pump blood out of the heart.
When comparing the ventricles with the atria, it is notable that the ventricles are larger than the atria. Each ventricle has to pump the same amount of blood as the opposite atrium, but the ventricles work under greater pressure, especially the left ventricle which must overcome the high resistance of the systemic circulation. This is why the ventricles, especially the left ventricle, have a much more muscular wall compared to the atria.