What is an arteriole?

An arteriole is defined as a very small artery that branches from a larger artery and leads into capillaries. Arterioles play a crucial role in regulating blood flow and blood pressure within the circulatory system. They are smaller than arteries and have more muscular and elastic walls, which allow them to adjust their diameter through vasoconstriction and vasodilation. This regulation is essential for directing blood to specific tissues based on their metabolic needs.

The structure and function of arterioles make them distinct from a large vein, which is responsible for returning blood to the heart. Additionally, arterioles are not types of capillaries, which are even smaller vessels where the actual exchange of gases and nutrients occurs. Similarly, muscle fibers pertain to the tissue composition in muscles and are unrelated to the vascular system. Understanding the roles of arterioles within the circulatory system is fundamental in grasping how blood flow is controlled throughout the body.