Central baroreflex resetting as a means of increasing and decreasing sympathetic outflow and arterial pressure. 2001

S E DiCarlo, and V S Bishop
Wayne State University School of Medicine, Detroit, Michigan 48201, USA. sdicarlo@med.wayne.edu

The arterial baroreflex has two important functions. First, the arterial baroreflex is a negative feedback reflex that regulates arterial pressure around a preset value called a set or operating point. Second, the arterial baroreflex also establishes the prevailing systemic arterial pressure when the operating point is reset. That is, modulating the response of barosensitive neurons in the central nervous system (CNS) establishes the operating point or prevailing systemic arterial pressure. Therefore, the operating point of the arterial baroreflex is not fixed, but is variable over a wide range of pressures and is determined by a variety of inputs from the peripheral and central nervous systems. At the onset of dynamic exercise, heart rate (HR) and sympathetic nerve activity (SNA) increase abruptly and dramatically. The initial increase in HR and SNA is mediated by central command. Central command operates by resetting the operating point of the arterial baroreflex to a higher pressure. In this situation, the operating point of the arterial baroreflex is above the prevailing arterial pressure, which elicits a blood pressure error. This error is corrected by activating SNA and inhibiting parasympathetic nerve activity, which increases cardiac output and peripheral resistance and, consequently, arterial pressure. After exercise, loss of central command and enhanced activity of the cardiopulmonary reflex resets the operating point of the arterial baroreflex to a lower pressure. In this situation, the operating point of the arterial baroreflex is below the prevailing arterial pressure, which elicits a blood pressure error. This error is corrected by inhibiting SNA, which decreases peripheral resistance and consequently arterial pressure. In these situations, central resetting of the arterial baroreflex is a means of increasing and decreasing sympathetic outflow and arterial pressure.

UI MeSH Term Description Entries
D008959 Models, Neurological Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment. Neurologic Models,Model, Neurological,Neurologic Model,Neurological Model,Neurological Models,Model, Neurologic,Models, Neurologic
D009043 Motor Activity Body movements of a human or an animal as a behavioral phenomenon. Activities, Motor,Activity, Motor,Motor Activities
D001794 Blood Pressure PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS. Systolic Pressure,Diastolic Pressure,Pulse Pressure,Pressure, Blood,Pressure, Diastolic,Pressure, Pulse,Pressure, Systolic,Pressures, Systolic
D002490 Central Nervous System The main information-processing organs of the nervous system, consisting of the brain, spinal cord, and meninges. Cerebrospinal Axis,Axi, Cerebrospinal,Axis, Cerebrospinal,Central Nervous Systems,Cerebrospinal Axi,Nervous System, Central,Nervous Systems, Central,Systems, Central Nervous
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D013564 Sympathetic Nervous System The thoracolumbar division of the autonomic nervous system. Sympathetic preganglionic fibers originate in neurons of the intermediolateral column of the spinal cord and project to the paravertebral and prevertebral ganglia, which in turn project to target organs. The sympathetic nervous system mediates the body's response to stressful situations, i.e., the fight or flight reactions. It often acts reciprocally to the parasympathetic system. Nervous System, Sympathetic,Nervous Systems, Sympathetic,Sympathetic Nervous Systems,System, Sympathetic Nervous,Systems, Sympathetic Nervous
D017704 Baroreflex A response by the BARORECEPTORS to increased BLOOD PRESSURE. Increased pressure stretches BLOOD VESSELS which activates the baroreceptors in the vessel walls. The net response of the CENTRAL NERVOUS SYSTEM is a reduction of central sympathetic outflow. This reduces blood pressure both by decreasing peripheral VASCULAR RESISTANCE and by lowering CARDIAC OUTPUT. Because the baroreceptors are tonically active, the baroreflex can compensate rapidly for both increases and decreases in blood pressure. Reflex, Baroreceptor,Baroreceptor Reflex,Baroreceptor Reflexes,Baroreflexes,Reflexes, Baroreceptor

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