Siegfried experiences a hemorrhage in an artery, and now blood is leaking out of

As blood exits the vasculature, there is a loss in blood volume, which in turn causes the systemic blood pressure to decrease. Baroreceptors (stretch receptors) in the carotid and artery walls are less stretched, and therefore their action potential firing frequency decreases. The baroreceptors project to the cardiovascular control center in the medulla oblongata. In response to decreased baroreceptor input, the cardiovascular control center stimulates sympathetic output and inhibits parasympathetic output. Sympathetic activity causes vasoconstriction and consequent increases in peripheral resistance and blood pressure. Decreased parasympathetic activity causes the SA node firing rate to increase and therefore heart rate increases. Combined with the sympathetic stimulation of the ventricles and consequent increase in contraction force, cardiac output increases as a result, also helping to increase blood pressure.