Why is the left ventricle smaller?

The left ventricle is not smaller; in fact, it is typically larger and more muscular than the right ventricle. This is because the left ventricle is responsible for pumping oxygenated blood to the entire body, requiring greater force and pressure compared to the right ventricle, which only delivers blood to the lungs. The thicker walls of the left ventricle accommodate this need for stronger contractions.