FIGURE 1

Schematic diagram of autonomic cardiovascular control. The cerebral cortex and hypothalamus project to the various nuclei within the medulla oblongata, where cardiovascular autonomic control is coordinated. The parasympathetic control of the cardiovascular system exits at the level of the brainstem via the vagus nerve. The preganglionic fibres of the vagus nerve then synapse with postganglionic parasympathetic neurons in ganglia on or near the target organ. Descending sympathetic pathways provide tonic control to SPN involved in cardiovascular control. SPN are found within the lateral horn of the spinal cord in segments T1–L2 and exit the spinal cord via the ventral root. They then synapse with postganglionic neurones located in the sympathetic chain (paravertebaral ganglia). Finally, the sympathetic postganglionic neurones synapse with the target organs, the heart and blood vessels