What is Vasodilators

e.g., nitrates, calcium antagonists, angiotensin
converting enzyme inhibitors, hydralazine, prazosin.
Put simply, vasodilators widen or open up blood vessels. With each
heart-beat blood is pumped out into the large elastic arteries. These branch
into smaller and smaller vessels called arterioles which convey it into the
muscles and internal organs before it returns to the heart through the veins.
The internal width of the arteries, arterioles and veins can be varied by
muscles in their tubular walls. By controlling the calibre of blood vessels in
different parts of the body, the circulation is adjusted to meet the changing
demands of the moment – for example, during muscular exertion. This is a
very fine balancing act which, in health, the body keeps under perfect
control. When things go wrong with the circulation vasodilators may help by
opening up (or dilating) arteries, arterioles or veins.