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Mechanotransduction of Cardiovascular Development and Regeneration
Published in Juhyun Lee, Sharon Gerecht, Hanjoong Jo, Tzung Hsiai, Modern Mechanobiology, 2021
Quinton Smith, Justin Lowenthal, Sharon Gerecht
About 4 weeks after conception, an endothelialized plexus facilitating the delivery of oxygen and nutrients has already been established, primed to support shear forces from the newly formed contracting heart [22]. The plasticity of the vasculature that develops is attuned to its specialized function, dependent upon the location within the body. As a result, there exists considerable variability in the structure and function of the endothelial, fibroblast, pericyte, and smooth muscle cell populations that make up the vasculature. Endothelial cells (ECs) arise after splanchnic mesoderm differentiation, similar to the rise of cells that will make up the endocardium. ECs emerge in a 2D fashion, until they coalesce to form3D tubular structures, coaxed by the ECM and signaling pathways involving the vascular endothelial growth factor (VEGF), FGF, and transforming growth factor (TGF-b). After de novo vasculogenesis, the established vasculature continues to branch and extend to the somatic mesoderm in a process termed “angiogenesis” [23].
Some Effects of the Environment on Emotions and their Relationships to Cardiovascular Diseases
Published in J. Rose, Human Stress and the Environment, 2021
There are several closely coordinated neurohormonal changes that pattern instinctual responses to an environmental challenge. The hypothalamic defense reaction is described1 as a highly differentiated response that overrides brainstem homeostatic mechanisms and adjusts the cardiovascular system in an anticipatory fashion that prepares it for vigorous physical activity to meet environmental challenges, and is thus highly suited for fight-flight. It is readily provoked in the conscious organism in response to any sudden or novel environmental stimulus and is characterized by increased cardiac output, vasodilatation in skeletal muscles, and vasoconstriction in the kidney, skin and particularly in the splanchnic area, with an acute rise of heart rate and blood pressure. The rise of cardiac output is directed to skeletal muscles and heart, and passively to the brain through a rise of perfusion pressure.2 The defense reaction thus elicits changes closely similar to those during strenuous muscular exercise, in which active muscle vasodilatation is produced by vasoactive metabolites in response to increased oxygen need.2
Syncope: Physiology, Pathophysiology and Aeromedical Implications
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
David A. Low, Christopher J. Mathias
Due to the hydrostatic gradient imposed by gravity on the cardiovascular system, syncope is most likely to occur in the upright posture due to arterial blood pressure at the brain being less than that at the heart and the pooling of blood below the heart. Thus, the effect of orthostatic stress on the cardiovascular system must be considered. Upon assumption of the upright posture, between 300 and 800 millilitres of blood is translocated to the lower limbs. The rise in pressure in the capillaries of the lower limbs also causes the movement of fluid from the blood to the tissues, resulting in plasma volume loss (Brown and Hainsworth, 1999). As a consequence of blood pooling and the superimposed decline in plasma volume, the return of venous blood to the heart is reduced and central blood volume falls (van Lieshout et al., 2003). Reductions in filling of the right ventricle lead to a reduction in stroke volume and a fall in cardiac output, despite an elevation of the heart rate (Harms et al., 1999), but blood pressure is preserved by compensatory vasoconstriction of resistance and capacitance vessels in the splanchnic, musculoskeletal, cutaneous and renal vascular beds (Rowell, 1984) (Figure 13.3).
Peregrine system infusion catheter for neurolytic renal denervation in hypertension: an overview of its safety and efficacy
Published in Expert Review of Medical Devices, 2023
Adam Janas, Wojciech Wojakowski
The answer to this problem may be to control sympathetic and parasympathetic activity in the nerves around the kidney artery by renal denervation (RDN). The renal efferent sympathetic nerves are mostly adrenergic [5]. Norepinephrine mediates vasoconstriction of the renal vessel as well as water and sodium reabsorption in renal tubular epithelial cells and renin release from juxtaglomerular cells [6]. Disruption of this pathway by RDN lowers blood pressure (BP) [7]. RDN increases renal sodium and water excretion by suppressing sympathetically mediated renin secretion and renal tubular sodium reabsorption [8]. The first-in-human experience with RDN was carried out by Freyberg and Peet in the late 1930s [9]. They surgically removed the major and minor splanchnic nerves and the lower dorsal sympathetic chain, leading to a huge BP reduction. However, the procedure has not won acclaim due to adverse events like hypotonia, syncope, incontinence, and erectile dysfunction [10]. Due to advancements in endovascular technology, RDN is now achievable in a transcatheter, minimally invasive way. Only, a few minimally invasive technologies are available to destroy nerves surrounding the renal artery and are part of the brain-kidney axis for BP control.
Impact of stressors in the aviation environment on xenobiotic dosimetry in humans: physiologically based prediction of the effect of barometric pressure or altitude
Published in Journal of Toxicology and Environmental Health, Part A, 2020
The parameters of interest included cardiac output, stroke volume, heart rate (or its inverse), regional blood flow (e.g., cerebral, splanchnic, and peripheral), pulmonary ventilation rate, alveolar ventilation rate, breathing frequency (or its inverse), tidal volume, breathing cycle parameters (inspiratory time, expiratory flow time, expiratory pause time, inspiratory duty cycle). Surrogate or normalized measures were acceptable. For example, alterations in cardiac index (cardiac output normalized to body surface area) were considered indicative of changes in cardiac output. Similarly, if physiological data were reported as fractional changes from baseline, this information was used to inform estimates of the relationship between altitude and the parameter alterations even if the baseline value of the parameter was not reported.
Patient-specific fluid–structure interaction model of bile flow: comparison between 1-way and 2-way algorithms
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Alex G. Kuchumov, Vasily Vedeneev, Vladimir Samartsev, Aleksandr Khairulin, Oleg Ivanov
The motor functions of the gallbladder and biliary tract are closely integrated with the rest of the digestive system by neurohormonal mechanisms that include the vagus and splanchnic nerves and various hormones among them cholecystokinin (CCK). The gallbladder contracting and discharging bile into the duodenum during fasting and digestive periods is controlled by CCK release (Çerçi et al. 2009).