What are capillaries primarily known for?

Capillaries are primarily known for their role in transporting blood, nutrients, and oxygen to cells. They are the smallest and most numerous blood vessels in the body, forming a network that connects arteries to veins. This extensive network allows for efficient exchange of oxygen, carbon dioxide, nutrients, and waste products between the blood and the surrounding tissues.

The walls of capillaries are very thin, consisting of a single layer of endothelial cells, which facilitates the diffusion process. Through these thin walls, oxygen from the blood can pass into the tissues, while carbon dioxide and other metabolic waste products move from the cells back into the bloodstream for removal. This direct exchange is essential for maintaining cellular function and overall homeostasis in the body.

In contrast, other choices describe functions not primarily associated with capillaries. For example, while hormones are transported through the bloodstream, this function is primarily handled by larger blood vessels rather than capillaries. Waste filtration is mainly a function of the kidneys and not the capillaries directly. Finally, blood storage is primarily the role of larger veins and specific organs like the spleen, rather than the capillary system. Thus, the central function of capillaries remains the delivery of oxygen and nutrients, as well as the removal