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πŸ“ The Yin And Yang Of Cardiac Autonomic Control: Vago-Sympathetic Interactions Revisited

Very interesting paper about the co-activation of Para-Sympathetic & Sympathetic nervous activity relating to the heart.

As you can see the Arch concept is valid.
During reciprocal control the range is bigger but during co-activation a more precise control is achieved. This is specifically toward the heart but I believe the same Arch can be applied to other areas as well.

β€œWe review the pattern of activity in the parasympathetic and sympathetic nerves innervating the heart. Unlike the conventional textbook picture of reciprocal control of cardiac vagal and sympathetic nervous activity, as seen during a baroreceptor reflex, many other reflexes involve simultaneous co-activation of both autonomic limbs. Indeed, even at drestT, the heart receives tonic drives from both sympathetic and parasympathetic cardiac nerves. Autonomic co-activation occurs during peripheral chemoreceptor, diving, oculocardiac, somatic nociceptor reflex responses as well as being evoked from structures within the brain. It is suggested that simultaneous co-activation may lead to a more efficient cardiac function giving greater cardiac output than activation of the sympathetic limb alone; this permits both a longer time for ventricular filling and a stronger contraction of the myocardium. This may be important when pumping blood into a constricted vascular tree such as is the case during the diving response. We discuss that in some instances, high drive to the heart from both autonomic limbs may also be arrhythmogenic. …
A general interpretation as to the role of reciprocal versus simultaneous co-activation of autonomic control is made by Berntson et al. [12]. Simultaneous co-activation allows precise control of the response direction, which is determined by the dominating limb of the autonomic nerve, and hence allows the fine tuning of target organ function. Since the dynamic range and the gain of the response is restricted in this situation, the tendency here is towards stabilization of the functional state of the target organ. In terms of reflex control of the heart this is important (e.g., during a dive) where the operating range needs to be confined but precisely controlled. In contrast, during reciprocal control, such as with baroreflex control of the heart, both the range and gain are massively increased in one direction or in the other due to the synergism of both limbs. This pattern is advantageous for guaranteeing response direction as well as high speed and large magnitude, but may be less efficient for precise adjustments.”

Updated on March 17, 2020

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