Arterial resistance

More than any other type of vessel, the arterioles are the main site of varying systemic resistance. The Vascular Smooth Muscle (VSM) in their walls allows for large changes in diameter. VSM contraction leads to vasoconstriction and VSM relaxation leads to vasodilation. Remember, R ? 1/r4. As the result of tonic sympathetic stimulation, all arterioles except those of the brain and lungs maintain a tonic state of contraction, in other words, they are always a little constricted. The ANS has control of blood vessel diameter through sympathetic stimulation that maintains vascular tone. To constrict vessels further, sympathetic stimulation is increased; to get dilation, there is a reduction in sympathetic stimulation.

Arteriole resistance is also influenced by local control. These factors usually act to match tissue blood flow to tissue's metabolic needs. For example, if some tissues have low O2 content, then blood flow to that region will increase (vessels dilate) to supply the tissues using up their O2. Conversely, if tissues have adequate O2 levels, then blood flow may decrease (vessels constrict) to that region. Reflex (long distance) vasoconstriction and vasodilation by the ANS and hormones is superimposed on the tonic control to ensure that arterial blood pressure remains adequate. Clinical note: Most cases of hypertension are associated with increased peripheral resistance.

Nice, you figured it out trin?

It is a bit much. LOL

Good stuff man