What are the smallest blood vessels that transport blood from the arteries into the body's tissues?

The smallest blood vessels that transport blood from the arteries into the body's tissues are indeed capillaries. Capillaries have very thin walls comprised of a single layer of endothelial cells, which allow for the efficient exchange of nutrients, gases, and waste products between the blood and surrounding tissues. This exchange is critical for maintaining homeostasis and supporting cellular functions.

In contrast, arteries are larger vessels that carry blood away from the heart, and they do not participate directly in nutrient and gas exchange. Veins are responsible for returning blood from the tissues back to the heart but are larger in diameter compared to capillaries. Venules are small vessels that collect blood from capillaries and merge to form veins, but they are still not as small as capillaries and do not carry out the direct exchange function. Thus, the role of capillaries as the smallest blood vessels is essential to understanding the circulatory system and its function in tissue perfusion.