Fig. 1.

Physical dangers, such as predators or changes in the surrounding environment, induce signaling from the cortex or the hypothalamus to nuclei located in the medulla. These nuclei project axons onto cell bodies located in the intermediolateral column of the T1 and L3 spinal cord. From there, cells synapse with postsynaptic ganglia located in the sympathetic trunk or in splanchnic ganglia throughout the body. In addition, presynaptic neurons innervate cells of the adrenal medulla to induce hormone production. Therefore, signaling from the sympathetic nervous system can affect tissues and cells located throughout the body