Final answer:
Local changes in the diameter of arterioles, controlled by vasoconstriction and vasodilation, are primarily responsible for regulating blood flow to the body's tissues. These small vessels adjust their diameter in response to various signals, which affects their resistance to blood flow and therefore regulates the distribution of blood.
Step-by-step explanation:
Local changes in the diameter of arteries and arterioles are most responsible for distributing blood to the various tissues and organs of the body. Arterioles, being small blood vessels with a lumen averaging 30 micrometers or less, play a key role in the regulation of blood flow to the body's tissues. They are sometimes referred to as resistance vessels because they have the ability to resist the flow of blood by means of changing their diameter through the processes of vasoconstriction and vasodilation.
Vascular tone, which refers to the partial contraction of smooth muscle in the vessel walls, plays a crucial role in maintaining a consistent diameter of the arterioles under resting conditions. The precise diameter of the lumen of an arteriole at any given moment is determined by a combination of neural and chemical signals that either prompt vasoconstriction, reducing blood flow, or vasodilation, increasing blood flow, ensuring the appropriate distribution of blood throughout the body.