China
Africa
Explore chapters and articles related to this topic
Diathermy therapy
Published in Riadh Habash, BioElectroMagnetics, 2020
Rehabilitation practice consists of a blended use of thermotherapy that is produced from diathermy devices leading to quicker and deeper heating to the patient. Heat may be used for therapeutic purposes, including rehabilitation practices in physiotherapy facilities or at home. For instance, heat improves blood circulation, enhances healing, increases soft tissue extensibility, decreases joint stiffness, and controls pain. Increased blood flow facilitates tissue healing by supplying protein, nutrients, and oxygen to the site of injury. For example, a 1ºC increase in tissue temperature is associated with a 10% to 15% increase in local tissue metabolism. Heat may be delivered to tissues via conduction, convection, or radiation. The extent of initial tissue necrosis is mainly determined by thermal power and energy applied to the tissue [62–64]. Primary physiological effects of heat include vasodilation and increased blood flow, increased metabolic rate, relaxation of muscle spasm, pain relief via the gate-control mechanism, reduced ischemia, and increased elasticity of connective tissue, as shown in Figure 7.4. Vasodilation, the opposite of vasoconstriction, is the increase in the interior diameter of blood vessels. Both vasodilation as well as vasoconstriction are automatically regulated by a properly functioning body. Vasodilation increases the delivery of nutrients and oxygen during the body during energy-consuming activities. Drugs and other physical agents, like heat, affect the diameter of a patient’s blood vessels.
Thermoregulation and Human Response to Heat
Published in Ken Parsons, Human Heat Stress, 2019
Blood flow influences the temperature of the skin, and sweating influences how wet it is. Blood perfuses through the whole body and generally takes on the temperature of the surrounding tissues. As it moves around the body, it therefore transports heat. If 1 L of blood transfers from the body core at 37°C to the skin, and returns from the skin at 36°C, then 3.85 kJ of heat will be lost (Sawka and Wenger, 1988). The distribution of blood around the body is determined by signals to blood vessels from the control system and by local effects. The rate of blood flow is determined by the heart. This includes heart rate and stroke volume. During exercise, muscles heat up and the heat is transported from the muscles by blood. When a person is experiencing heat stress, vasodilation allows more blood to flow to the skin surface. An increase in skin temperature increases heat loss (or reduces heat gain) by convection and radiation. It is particularly effective in the limbs (arms, hands, fingers, legs, feet, and toes) as they have a large surface area-to-mass (volume) ratio. In hot conditions, countercurrent heat exchange is avoided. This is where cool venous blood runs next to warm arterial blood, transferring and transporting heat back to the body. Blood also flows to the skin surface, avoiding circumstances which direct arterial blood directly to venules via small blood vessels called anastomoses. These mechanisms are used to preserve body heat when cold and are therefore not employed when hot.
Cardiovascular System:
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
The properties of the blood vessels change as the blood moves from the elastic arteries into the muscular arteries. The muscular arteries have the thickest tunica media layer and contain relatively more smooth muscle and less elastic tissue than the elastic arteries. Thus, they are less distensible than the elastic arteries but are able to contribute to vasoconstriction. They range in size from 3 to 10 mm in diameter. The smallest arteries are called the arterioles, ranging in size from 10 µm to 0.3 mm. The larger arterioles contain all three tunicae, but as they decrease in size closer to the capillary bed, they become more like the capillary walls. Like the muscular arteries, they contain a high proportion of smooth muscle, which usually has some vascular tone (a condition of partial vasoconstriction). The diameter of the arterioles is a large determinant in the amount blood flow entering a connecting capillary bed. Vasoconstriction can be triggered by a change in sympathetic tone or by local effects such as a rise in O2, decrease in CO2, and cold. Conversely, vasodilation occurs when the smooth muscle relaxes, in response to local effectors such as high CO2, high temperature, and histamine. As the blood leaves the arterioles, the pulsatile flow reduces to smooth flow.
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
Applying vacuum over the lanced site leads to increased blood release (Figure 4B). The extent of vacuum and the length of time over which it is applied are positively correlated with the volume of blood released. The Microlet Vaculance Lancing device (Bayer, West Haven, CT) uses a plunger mechanism to actuate the lancet to pierce the skin and create a vacuum around the puncture site to draw blood to the skin’s surface [74]. Stretching the skin up into the nosepiece by applying a vacuum before lancing results in a larger volume of blood extracted from the lancet wound [76]. The application of vacuum before and after lancing the forearm, combined with skin stretching, can collect approximately 16 µL of blood in 30s [76]. This technique induces vasodilation and an up to fivefold increase in blood perfusion. With the application of vacuum, redness and bruising were experienced in some cases by the participants but were resolved in a few days [76]
Impact of sedentarism due to the COVID-19 home confinement on neuromuscular, cardiovascular and metabolic health: Physiological and pathophysiological implications and recommendations for physical and nutritional countermeasures
Published in European Journal of Sport Science, 2021
Marco Narici, Giuseppe De Vito, Martino Franchi, Antonio Paoli, Tatiana Moro, Giuseppe Marcolin, Bruno Grassi, Giovanni Baldassarre, Lucrezia Zuccarelli, Gianni Biolo, Filippo Giorgio di Girolamo, Nicola Fiotti, Flemming Dela, Paul Greenhaff, Constantinos Maganaris
During exercise, sheer stress and other hemodynamic stimuli induce positive effects on the peripheral circulation, favouring vasodilation, proliferation of blood vessels and an anti-atherogenic phenotype. Inactivity inevitably goes in the opposite direction. According to Boyle et al. (2013) a reduction of physical activity to <5000 steps/day for only a few days impairs flow-mediated vasodilation. Preliminary data from our group suggest that 10 days of bed rest induces, in healthy young subjects, an impaired microvascular function, as shown by a blunted blood flow increase during passive leg movement of one leg (an index of nitric oxide [NO]-mediated vasodilation [Gifford & Richardson, 2017]) (Zuccarelli et al., 2020), and by a less pronounced reactive microvascular hyperaemia following a transient ischaemia, in association with signs of impaired NO metabolism (Porcelli et al., 2020).
Enhanced adsorption of nicotinic acid by different types of Mg/Al layered double hydroxides: synthesis, equilibrium, kinetics, and thermodynamics
Published in Journal of Dispersion Science and Technology, 2020
Nicotinic acid (NAc) is a benzoic acid derivative containing a carboxylic acid group. It is a water-soluble vitamin obtained by fermentation, and is also known as Niacin or vitamin B3. The vitamin effects of NAc were discovered at the beginning of the 20th century. In the following years, NAc was found to have a low cholesterol effect in plasma, and so it began to be used to treatment of dyslipidemia.[17,18] Although NAc aids in reducing free fatty acids in plasma, it can cause side effects when more than the recommended amount is consumed. The vasodilator response, which is one of the main side effects, leads to a decrease in blood pressure. However, other common undesirable effects include nausea, abdominal pain and diarrhea, as well as rashes, itching, and redness. Each year, large amounts of NAc are produced and inevitably discharged into the wastewater system. Thus, adsorption as one of the most preferred separation methods is a cheap and effective approach to separating NAc from aqueous solutions.[19]