How is blood pressure maintained?
The blood pressure is maintained by both nervous impulses and circulating hormones. Stimulating the sympathetic nervous system raises the blood pressure and stimulating the parasympathetic nervous system tends to lower it. The hormones particularly involved are adrenaline and noradrenaline (epinephrine and norepinephrine) which are secreted by the adrenal glands in response to sympathetic stimulation. The control is from the cardiovascular centres in the midbrain, which receive information from the pressure sensors (baroreceptors) in the carotid sinus and aortic arch (not in the veins).
