Part of “CHAPTER 1 – ENDOCRINOLOGY AND THE ENDOCRINE PATIENT“

Although speaking in terms of the cardiovascular, respiratory, gastrointestinal, and nervous systems is convenient, the endocrine system anatomically and functionally overlaps with all body systems (see Part X). Extensive overlap is found between the endocrine system and the nervous system (see Chap. 175 and Chap. 176). Hormonal peptides are synthesized in the cell bodies of neurons, are transported along axons to nerve terminals, and are released at the nerve endings. Within these neurons, they coexist with classic neurotransmitters and often are coreleased with them. These substances play a role in neuromodulation or neurosecretion by means of the extracellular fluid. The nerves in which peptide hormones appear to play a role in the transmission of information are called peptidergic nerves.20 It is the ample similarity of ultrastructure, histochemistry, and hormonal contents of nerve cells and of many peptide-secreting endocrine cells that has led to the concept of the diffuse neuroendocrine system.