Complex sentence: The CNS regulates the immune system through neuroendocrine pathways and the HPA axis is the most important neuroendocrine pathway as it is responsible for modulating inflammatory responses that occur throughout the body.
Split into simpler sentences: The CNS regulates the immune system through neuroendocrine pathways and the HPA axis is the most important neuroendocrine pathway. The HPA axis is responsible for modulating inflammatory responses that occur throughout the body.