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Regulation of Arterial Blood Pressure
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The arterial baroreceptor reflex is the most important mechanism of the short-term regulation of blood pressure. The mean arterial blood pressure is determined by the amount of blood in the arterial system at any point in time. The volume of blood in the arteries is determined by the amount of blood entering the aorta as cardiac output and the blood volume leaving the arteries as peripheral runoff into the capillaries. The cardiac output is the product of heart rate and stroke volume, and the peripheral runoff is determined by the mean arterial blood pressure acting across the total peripheral resistance of the arterioles. The main determinants of mean arterial blood pressure are therefore the cardiac output and the total peripheral resistance acting via changes in the arterial blood volume. The negative feedback arterial baroreceptor reflex influences many factors controlling cardiac output, peripheral resistance and arterial blood pressure (Figure 31.4).
Developmental Aspects of Reflex Control of the Circulation
Published in Irving H. Zucker, Joseph P. Gilmore, Reflex Control of the Circulation, 2020
The arterial baroreceptor reflex was the earliest recognized, and the baroreceptors (carotid sinus and aortic arch) are today usually considered the major feedback elements of the cardiovascular controlling system (cf. references in Gootman, 1983). While control of arterial pressure is the chief function of these reflexes, there is a cardiac component of change in heart rate and contractile force. While baroreceptor reflexes are present at birth, there appear to be differences in their postnatal maturation (Gootman, 1983; Gootman et al., 1979, 1987a) in the pig, dog, and rat, but there is some controversy as to whether this is true for the lamb (Hanson, 1988). Table 1 summarizes the information available on the baroreflex responses at different ages in the perinatal period of different mammals (Gootman, 1983; Gootman et al., 1979, 1987a).
Serotonergic Mechanisms in Baroreceptor Afferent Processing and Cardiovascular Control By the NTS
Published in I. Robin A. Barraco, Nucleus of the Solitary Tract, 2019
The essential role of arterial baroreceptors, which are mainly located within the arterial wall in the region of the aortic arch and carotid sinus, is to buffer any deviation of arterial BP through a reflex mechanism normally called the baroreceptor reflex. The impulses arising from stimulation of these mechanoreceptors by arterial dilatation initiate this reflex. In summary, it is now well accepted that the cell bodies of aortic and carotid sinus baroreceptor neurons are located within the nodose ganglion (NG) and the petrosal ganglion, respectively. These neurons are thus considered as the first-order neurons in the baroreceptor reflex arc. The primary afferents of the IXth and Xth cranial nerves convey the impulses generated in the carotid and aortic regions, respectively, to the second-order neurons of this reflex arc, located nearly exclusively in the NTS. It is also now well accepted that baroreceptor afferent messages are first integrated in the NTS and then in the regions of the ventrolateral medulla (VLM), where the cell bodies of neurons involved in the control of sympathetic and vagal discharge to the heart and blood vessels are located. In several reviews, such as the recent one by Kumada et al.8 as well as in other chapters of this book, the reader will find all the relevant information from the literature concerning the above-mentioned concepts described in detail.
Autonomic nervous system assessment using heart rate variability
Published in Acta Cardiologica, 2023
Jean-Marie Grégoire, Cédric Gilon, Stéphane Carlier, Hugues Bersini
The interpretation of the LF band (0.04–0.15 Hz) is more complex. Sympathetically mediated blood pressure oscillations (Mayer waves) are slower than respiration and are reflected in the HRV spectrum [31]. As a result, the LF band indirectly represents at least part of the adrenergic activity. It is related to the baroreceptor reflex. Thus, part of the LFs comes from vagal activity because this reflex is mediated by the vagus nerve. As a result, vagal or adrenergic participation in the LF band is highly variable depending on the position and activity of the subjects. This variable participation complicates interpretation and invalidates the fact that LFs can be considered solely representative of adrenergic activity. Eckberg also suggested that central mechanisms may play a role in addition to the baroreflex [32]. Thus, the interpretation of LFs as solely representative of adrenergic activity should be avoided.
Baroreflex control model for cardiovascular system subjected to postural changes under normal and orthostatic conditions
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
V. L. Resmi, R. G. Sriya, N. Selvaganesan
An integrated mathematical model is proposed which consist of baroreflex control along with the cardiovascular system. The proposed model determines the dynamical interaction among blood pressure, parameters that control it and the baroreflex mechanism. This model consists of:Cardiovascular system that utilizes a simple resistance-compliance model to replicate the flow of blood in the vasculature and a heart model proposed by Mulier (Ottesen 1997). Both pulsatile and non pulsatile models are considered for the simulation of the proposed integrated model.Baroreceptor reflex consisting of (i) Baroreceptors modeled as mechanoreceptors using stress strain based voigt model (ii) Central nervous system modeled using Hodgkin-Huxley model and (iii) Efferent pathways modeled using dynamics of chemical reactions that control HR, stroke volume, venous compliance and contractility (Ottesen 1997; Samaan and Stella 1935).
Pancreatic exocrine insufficiency in diabetes is associated with autonomic dysfunction
Published in Scandinavian Journal of Gastroenterology, 2021
Dag André Sangnes, Elisabeth Sandvik Bergmann, Rose Marie Moss, Trond Engjom, Eirik Søfteland
In addition to the association with PEI, autonomic dysfunction in diabetes is associated with other gastrointestinal complications, as well as increased cardiovascular mortality [16,29–31]. To assess autonomic dysfunction in this study, we used standardized methods for detecting cardiac autonomic neuropathy [16]. Heart rate variability at rest is a general measure of the body’s ability to alter the heart rate to meet the physiological demand, while the baroreflex sensitivity test investigates the parasympathetic nerve fibres’ ability to adjust the heart rate in response to changes in respiration-induced blood pressure fluctuation [16,29]. Whereas reduced heart rate variability and impaired baroreceptor reflex may occur early in diabetes, orthostatic hypotension often develops at a later stage and might also represent sympathetic dysfunction [16]. This may explain why our PEI patients had reduced heart rate variability and baroreflex sensitivity compared to controls, while we could not find any differences in orthostatic blood pressure.