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Beginning in the sympathetic nervous system, an external stimulus affects the adrenal medulla and causes a release of catecholamines. The sympathoadrenal system is a physiological connection between the sympathetic nervous system and the adrenal medulla and is crucial in an organism's physiological response to outside stimuli. [1]
The adrenal medulla is the principal site of the conversion of the amino acid tyrosine into the catecholamines; epinephrine, norepinephrine, and dopamine. Because the ANS, specifically the sympathetic division, exerts direct control over the chromaffin cells , the hormone release can occur rather quickly. [ 2 ]
Parasympathetic action helps in digestion and absorption of food by increasing the activity of the intestinal musculature, increasing gastric secretion, and relaxing the pyloric sphincter. It is called the “rest and digest” division of the ANS. [24] The parasympathetic nervous system decreases respiration and heart rate and increases digestion.
In the parasympathetic division, neurons are cholinergic. That is to say acetylcholine is the primary neurotransmitter responsible for the communication between neurons on the parasympathetic pathway. In the sympathetic division, neurons are mostly adrenergic (that is, epinephrine and norepinephrine function as the primary neurotransmitters).
The myenteric plexus (or Auerbach's plexus) provides motor innervation to both layers of the muscular layer of the gut, having both parasympathetic and sympathetic input (although present ganglion cell bodies belong to parasympathetic innervation, fibers from sympathetic innervation also reach the plexus), whereas the submucous plexus provides secretomotor innervation to the mucosa nearest the ...
Parasympathetic ganglia are the autonomic ganglia of the parasympathetic nervous system. Most are small terminal ganglia or intramural ganglia, so named because they lie near or within (respectively) the organs they innervate. The exceptions are the four paired parasympathetic ganglia of the head and neck.
Adrenal pheochromocytomas are usually benign while extra-adrenal ones are more malignant. [3] They are most of the time in the adrenals, and only rarely outside of the abdomen. They usually secrete hormones and estimates of a familial history vary. [1] [2] Nonchromaffin paragangliomas are usually benign. [3]
Chromaffin cells, also called pheochromocytes (or phaeochromocytes), are neuroendocrine cells found mostly in the medulla of the adrenal glands in mammals.These cells serve a variety of functions such as serving as a response to stress, monitoring carbon dioxide and oxygen concentrations in the body, maintenance of respiration and the regulation of blood pressure. [1]