What do venules primarily collect?

Venules primarily collect blood from capillaries. Capillaries are the smallest blood vessels where the exchange of gases, nutrients, and waste products occurs between the blood and surrounding tissues. After this exchange, the depleted blood, now low in oxygen and high in carbon dioxide, enters the venules. The primary function of venules is to gather this deoxygenated blood from the capillary beds and transport it back toward larger veins, ultimately leading to the heart.

By understanding this process, one can see that the role of venules is crucial in the circulatory system, serving as a transition point for blood returning from the tissues. This sets them apart from other structures such as arteries, which carry oxygenated blood away from the heart.