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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 consists of irregularly shaped cells grouped around blood vessels. These cells are intimately connected with the sympathetic division of the autonomic nervous system (ANS). These adrenal medullary cells are modified postganglionic neurons, and preganglionic autonomic nerve fibers lead to them directly from the central ...
The cell that sends its fiber is called a preganglionic cell, while the cell whose fiber leaves the ganglion is called a postganglionic cell. As mentioned previously, the preganglionic cells of the sympathetic nervous system are located between the first thoracic segment and the third lumbar segments of the spinal cord.
An example of a neuroendocrine cell is a cell of the adrenal medulla (innermost part of the adrenal gland), which releases adrenaline to the blood. The adrenal medullary cells are controlled by the sympathetic division of the autonomic nervous system. These cells are modified postganglionic neurons. Autonomic nerve fibers lead directly to them ...
These cells then undergo a second migration from the dorsal aorta to form the adrenal medulla and other organs of the sympathetic nervous system. [44] Cells of the adrenal medulla are called chromaffin cells because they contain granules that stain with chromium salts, a characteristic not present in all sympathetic organs.
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]
They are a neural crest derivative and share a common sympathoadrenal precursor cell with sympathetic neurons and chromaffin cells (adrenal medulla). Although an autonomic ganglion is the site where preganglionic fibers synapse on postganglionic neurons, the presence of small interneurons has been recognized.
Another notable structure is the medulla of the adrenal gland, where chromaffin cells function as modified post-ganglionic nerves. Instead of releasing epinephrine and norepinephrine into a synaptic cleft, these cells of the adrenal medulla release the catecholamines into the blood stream as hormones. [1]