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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 ]
Therefore, this response that acts primarily on the cardiovascular system is mediated directly via impulses transmitted through the sympathetic nervous system and indirectly via catecholamines secreted from the adrenal medulla. The sympathetic nervous system is responsible for priming the body for action, particularly in situations threatening ...
Pituitary gland tumors are very common in the canine. A productive form arising from the anterior pituitary is the primary cause of Cushing's disease of dogs. This tumor causes excessive production of cortisol from the adrenal cortex which leads to the classic signs of alopecia (hair loss), polyuria (excessive urination), polydipsia (excessive water drinking), and a pot-bellied appearance of ...
When an adrenal nodule (potential tumor) is discovered on computed tomography or magnetic resonance imaging, there is a 5–10% chance the lesion is a pheochromocytoma. [175] The incidence of adrenal tumors is found in the infographic above, with pheochromocytoma noted in yellow in the top right corner.
They are concentrated near the adrenal glands and essentially function the same way as the adrenal medulla. They are sometimes found in connection with the ganglia of other sympathetic plexuses . None have been found with the sympathetic ganglia associated with the branches of the trigeminal nerve .
The sympathetic nervous system's activation provides for these needs. A similar example involving fight is of a cat about to be attacked by a dog. The cat shows accelerated heartbeat, piloerection (hair standing on end), and pupil dilation, all signs of sympathetic arousal. [23] Note that the zebra and cat still maintain homeostasis in all states.
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]