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Wearable Sensors for Blood Perfusion Monitoring in Patients with Diabetes Mellitus
Published in Andrey V. Dunaev, Valery V. Tuchin, Biomedical Photonics for Diabetes Research, 2023
Evgenii A. Zherebtsov, Elena V. Zharkikh, Yulia I. Loktionova, Angelina I. Zherebtsova, Viktor V. Sidorov, Alexander I. Krupatkin, Andrey V. Dunaev
Regulation in smooth muscle vessels is concerned with the diameter of these vessels and, as a result, with the volumetric blood flow. The contractile state of smooth muscle cells establishes the vessel diameter of a required size, which ensures active tonic tension for a long time, i.e., to maintain proper vascular tone (Table 5.2). Small arteries and arterioles play a major role in maintaining resistance to blood flow.
The Microcirculation Physiome
Published in Joseph D. Bronzino, Donald R. Peterson, Biomedical Engineering Fundamentals, 2019
Aleksander S. Popel and Roland N. Pittman
where Q is the volumetric ow rate. For a Newtonian uid, the apparent viscosity becomes the dynamic viscosity of the uid and the above equation represents Poiseuille’s law. e apparent viscosity is a function of hematocrit, vessel radius, blood ow rate, and other parameters. In the microcirculation, blood ows through a complex branching network of arterioles, capillaries, and venules. Arterioles are typically 10-150 μm in diameter, capillaries are 4-8 μm, and venules are 10-200 μm. Now, we will discuss vascular wall mechanics and blood ow in vessels of dierent size in more detail.
Biological Responses in Context
Published in Arthur T. Johnson, Biology for Engineers, 2019
The same cardiovascular control system regulates blood distribution and blood pressure by affecting the small arterioles of the peripheral blood vasculature. The entrance to each of these vessels is surrounded by a sphincter muscle (a ring of involuntary muscle that surrounds the arteriolar aperture) with sympathetic, and in some cases, parasympathetic, nerve fibers. The sphincter is usually contracted. When the signal comes for the muscle to relax, the neuron produces nitric oxide at the neuromuscular junction, and this gas relaxes the sphincter. When the sphincter muscle expands, it increases the area through which blood flows and decreases its resistance. With decreased resistance, blood pressure falls.
Minimally invasive capillary blood sampling methods
Published in Expert Review of Medical Devices, 2023
Michael S. F. Hoffman, James W. McKeage, Jiali Xu, Bryan P. Ruddy, Poul M. F. Nielsen, Andrew J. Taberner
Blood release enhancing techniques aim to increase the volume of blood delivered through broken capillaries to the site of skin penetration. Such techniques may also enable less painful methods that would otherwise release insufficient blood volume to be adopted. Blood flow through capillaries is controlled by upstream myogenic regulation of arterioles that constrict and dilate in response to neuronal stimuli [72]. Physical manipulation of the tissue is the most prevalent method, applying pressure in the surrounding region so as to ‘milk’ it for blood.