<Table> <Tr> <Td> </Td> <Td> This article does not cite any sources . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2009) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article does not cite any sources . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2009) (Learn how and when to remove this template message) </Td> </Tr> <P> The cardiovascular centre is a part of the human brain responsible for the regulation of the rate at which the heart beats through the nervous and endocrine systems . It is found in the medulla oblongata . Normally, the heart beats without nervous control, but in some situations (e.g., exercise, body trauma), the cardiovascular centre is responsible for altering the rate at which the heart beats . It also mediates respiratory sinus arrhythmia . </P> <P> When a change of blood pH is detected by central chemoreceptors or by peripheral chemoreceptors in aortic bodies and in carotid bodies, or a change of blood pressure is detected by baroreceptors in the aortic sinuses or carotid sinuses, the cardiovascular centre affects changes to the heart rate by sending a nerve impulse to the cardiac pacemaker (or SA node) via sympathetic fibres (to cause faster and stronger cardiac muscle contraction) and the vagus nerve (to cause slower and less strong cardiac muscle contraction). The cardiovascular centre also increases the stroke volume of the heart (that is, the amount of blood it pumps). These two changes help to regulate the cardiac output, so that a sufficient amount of blood reaches tissue . </P>

Where is the major cardiovascular center in the cns