This area is outside the blood brain barrier, and is therefore readily exposed to substances circulating through the blood and cerebral spinal fluid. Common triggers of the CTZ include metabolic abnormalities, toxins, and medications. Activation of the CTZ is mediated by dopamine (D2) receptors, serotonin (5HT3) receptors, and neurokinin receptors (NK1). Vestibular system: This system is activated by disturbances to the vestibular apparatus in the inner ear. These include movements that cause motion sickness and dizziness. This pathway is triggered via histamine (H1) receptors and acetylcholine (ACh) receptors. Peripheral Pathways: These pathways are triggered via chemoreceptors and mechanoreceptors in the gastrointestinal tract, as well as other organs such as the heart and kidneys. Common activators of these pathways include toxins present in the gastrointestinal lumen and distension of the gastrointestinal lumen from blockage or dysmotility of the bowels. Signals from these pathways travel via multiple neural tracts including the vagus, glossopharyngeal, splanchnic, and sympathetic nerves.Signals from any of these pathways then travel to the brainstem, activating several structures including the nucleus of the solitary tract, the dorsal motor nucleus of the vagus, and central pattern generator. These structures go on to signal various downstream effects of nausea and vomiting. The bodys motor muscle responses involve halting the muscles of the gastrointestinal tract, and in fact causing reversed propulsion of gastric contents towards the mouth while increasing abdominal muscle contraction. Autonomic effects involve increased salivation and the sensation of feeling faint that often occurs with nausea and vomiting.
In the treatment of umbilical granulomas, silver nitrate is applied to the umbilical site to burn off the excess tissue. The absence of nerve endings within the granuloma make this a painless treatment for the newborn. While painless, contact of silver nitrate to the adjacent, healthy, normal tissue may result in burns. Silver nitrate application to the infected site should not exceed three applications with an interval of 3-4 days. In this event, alternative treatments should be considered Following treatment with silver nitrate, the granuloma is expected to shrink and resolve within 7 days. Double-ligature treatment
In cases with deeply located umbilical granulomas, the double-ligature technique can be utilized to ligate the base of the granuloma. The procedure involves prepping and sterilizing the umbilical area with iodine solution, placing a silk suture around the base of the lesion to keep in place, and finally placing a more exact ligature around the granuloma. Much like the normal process of umbilical cord residue healing, the ligated granuloma will necrose due to lack of blood supply and will fall off naturally within 1 to 2 weeks. Minor complications of this technique include minimal bleeding and possibly requiring more ligatures than the original double ligation. Cryocautery
Cryocautery can be utilized to freeze the umbilical granuloma by using cryogenic nitrous oxide along with other equipment. During cryocautery procedures, the umbilical site is first cleaned. The physician will then hold a cyroprobe with nitrous oxide as a refrigerant directly to the granuloma for 3 minutes.