The walls of arterioles contain muscles. How are these muscles important in controlling blood flow?
All blood vessels including the arteries, the arterioles, the capillaries, the venules and the veins have a layer of smooth muscle tissue that forms part of their anatomical structure.
The blood vessels only play a passive role in the transportation of blood which is pumped by the heart. They have no role to play in peristalsis. The muscle layer though can be used to change the diameter of the blood vessels and this can influence the blood flow by a large extent.
This process called vasodilation and vasoconstriction controls the amount of blood that is transported to the lower body organs and also helps in the regulation of body temperature.
The change in diameter of blood vessels is influenced by various hormones and chemicals created in the nervous system like vasopressin, epinephrine, angiotensin, etc. These help in increasing or decreasing the amount of blood being sent to specific organs as the requirements of the body change.