the adrenal gland produces epinephrine, which is necessary for the sympathetic nervous system to function.
the adrenal gland produces epinephrine, which is necessary for the sympathetic nervous system to function.
what does the adrenal gland produce that is necessary for the sympathetic nervous system to function?
epinephrine
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. when the body receives sensory information, the sympathetic nervous system sends a signal to preganglionic nerve fibers, which activate the adrenal medulla through acetylcholine. once activated, norepinephrine and epinephrine are released directly into the blood by postganglionic nerve fibers where they act as the bodily mechanism for "fight-or-flight" responses. because of this, the sympathoadrenal system plays a large role in maintaining glucose levels, sodium levels, blood pressure, and various other metabolic pathways that couple with bodily responses to the environment. during numerous diseased states, such as hypoglycemia or even stress, the body’s metabolic processes are skewed. the sympathoadrenal system works to return the body to homeostasis through the activation or inactivation of the adrenal gland. however, more severe disorders of the sympathoadrenal system such as phaeochromocytoma (a tumor on the adrenal medulla) can affect the body’s ability to maintain a homeostatic state. in such cases, curative agents such as adrenergic agonists and antagonists are used to modify epinephrine and norepinephrine levels released by the adrenal medulla.
sympathoadrenal system
cannon’s proposed the existence and functional unity of the sympathoadrenal (or “sympathoadrenomedullary” or “sympathico-adrenal”) system. he theorized that the sympathetic nervous system and the adrenal gland work together as a unit to maintain homeostasis in emergencies. to identify and quantify adrenaline release during stress, beginning in about 1919 cannon exploited an ingenious experimental setup. he would surgically excise the nerves supplying the heart of a laboratory animal such as a dog or cat. then he would subject the animal to a stressor and record the heart rate response. with the nerves to the heart removed, he could deduce that if the heart rate increased in response to the perturbation, then the increase in heart rate must have resulted from the actions of a hormone. finally, he would compare the results in an animal with intact adrenal glands with those in an animal from which he had removed the adrenal glands. from the difference in the heart rate between the two animals, he could infer further that the hormone responsible for the increase in heart rate came from the adrenal glands. moreover, the amount of increase in the heart rate provided a measure of the amount of hormone released. cannon became so convinced that the sympathetic nervous system and adrenal gland functioned as a unit that in the 1930s he formally proposed that the sympathetic nervous system uses the same chemical messenger—adrenaline—as does the adrenal gland. cannon’s notion of a unitary sympathoadrenal system persists to this day. researchers in the area have come to question the validity of the notion of a unitary sympathoadrenal system, although clinicians often continue to lump together the two components.
walter bradford cannon