Intrinsic nerve plexuses

Explain how the following mechanisms regulate activity of the digestive system intrinsic nerve plexuses, extrinsic autonomic nerves, and gastrointestinal hormones... 

The gastric phase, which occurs when food actually enters the stomach. The presence of food and the composition of gastric contents stimulate local reflexes involving intrinsic nerve plexuses and stretch receptors and initiate release of gastrin from G cells to further enhance secretion. 

Yamamoto Y, Atoji Y, Suzuki Y (1995) Nerve endings in bronchi of the dog that react with antibodies against neurofllament protein. J Anat 187 (Pt l) 59-65 Yamamoto Y, Ootsuka T, Atoji Y, Suzuki Y (1998) Morphological and quantitative study of the intrinsic nerve plexuses of the canine trachea as revealed by immunohistochemical staining of... 

The intrinsic primary afferent neurons are present in both the myenteric and submucosal plexuses. They respond to luminal chemical stimuli, to mechanical deformation of the mucosa, and to stretch. The nerve endings of the primary afferent neurons can be activated by endogenous substances (e.g., serotonin) arising from local enterochromaffin cells or possibly from serotonergic nerves. 

Generally speaking, the clinically relevant structures of the thoracic outlet region are the brachial plexus nerves, the subclavian artery and the subclavian vein. The causes of brachial plexopathy include trauma, intrinsic and extrinsic tumors, radiation plexopathy and Parsonage-Turner syndrome. The neurovascular structures of the thoracic outlet... 

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