neuroendocrine
Meaning of neuroendocrine: Describing the crossover point at which a nerve impulse ends in a hormone released into the blood rather than a message to the next cell.
Definition of neuroendocrine
Neuroendocrine describes the connection between the nervous system and the hormone-producing glands. A neuroendocrine cell receives signals in the way a nerve cell does but responds by releasing a hormone into the bloodstream, so a rapid electrical message is converted into a slower chemical one capable of acting on distant organs.
Where does the crossover happen?
| Site | Signal in | Hormone out |
|---|---|---|
| Hypothalamus | Nerve signals from the rest of the brain | Releasing hormones that control the pituitary |
| Back of the pituitary | Nerve endings reaching down from the hypothalamus | Vasopressin and oxytocin |
| Core of the adrenal gland | Sympathetic nerve fibers | Adrenaline |
| Lining of the gut | Stretch and the chemical contents of the bowel | Hormones controlling digestion and appetite |
Why does the body need it?
The two systems have opposite strengths. The nervous system is fast and precise but reaches only where its wires go. The endocrine system is slower but reaches everywhere at once through the blood. A threat needs both: sympathetic nerves act within a fraction of a second, and adrenaline released from the adrenal gland sustains the response for minutes afterward. The stress axis running from hypothalamus to pituitary to adrenal cortex is the classic example, complete with feedback in which the final hormone damps down the signals that produced it. The same architecture governs thyroid activity, growth, reproduction and the balance of water and salt, so most of the endocrine system is neuroendocrine at its upper end.
What are neuroendocrine tumors?
Growths arising from these cells, which are scattered rather than gathered into a single organ. That scattering is why a neuroendocrine tumor may appear in the small bowel, pancreas, lung, appendix, stomach or elsewhere. Some secrete hormones and announce themselves with distinctive patterns such as flushing, diarrhea or repeated low blood sugar. Others secrete nothing and are found incidentally or once they have grown. They range from slow-growing tumors compatible with many years of life to aggressive high-grade cancers, and they are recognized in the laboratory by stains for proteins these cells share.
Why is the word used so loosely?
Because it describes a property rather than a place. A cell is called neuroendocrine when it behaves in this dual way, so pathologists apply the label to tissue in organs that have nothing else in common, and a report naming it says what the cells are doing rather than where they came from.
Used in a sentence
The biopsy stained positive for synaptophysin, supporting a neuroendocrine origin.
Good to know
Neuroendocrine cells are scattered through the gut, lung and pancreas rather than gathered into one organ, which is why tumors arising from them turn up in so many different sites.
Word origin
Where “neuroendocrine” comes from
Neuro comes from the Greek neuron, meaning nerve; endocrine joins endon, meaning within, with krinein, meaning to separate, describing secretion inward rather than outward.