Tone, also known as vascular tone, describes the diameter and tone of a blood vessel when it is fully dilated. All arteries and veins show some degree of smooth muscle contraction that affects the tone of the vessel.
The Vascular tone varies among different organs. The vascular tone of the pulmonary system may be different than that of the coronary vascular system. The vascular tone of blood vessels and arteries determine how hard the heart has to work to pump blood throughout the body.
When there is no resistance from blood vessels, the heart is able to pump smoothly – reducing the risk of heart disease. The higher the resistance from blood vessels, the harder the heart has to pump, the higher the risk of heart disease.
Too much resistance pushing against artery walls is known as high blood pressure or hypertension. High blood pressure will, over the course of time, damage the walls of the larger arteries, such as the aorta and carotids, as well as the smaller ones, the cerebral, coronary and renal arteries. High blood pressure makes the heart work harder pumping blood throughout the body.