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Windkessel Effect
Windkessel effect (German: Windkesseleffekt) is a term used in medicine to account for the shape of the arterial blood pressure waveform in terms of the interaction between the stroke volume and the compliance of the aorta and large elastic arteries (Windkessel vessels) and the resistance of the smaller arteries and arterioles. Windkessel when loosely translated from German to English means 'air chamber', but is generally taken to imply an ''elastic reservoir''. The walls of large elastic arteries (e.g. aorta, common carotid, subclavian, and pulmonary arteries and their larger branches) contain elastic fibers, formed of elastin. These arteries distend when the blood pressure rises during systole and recoil when the blood pressure falls during diastole. Since the rate of blood entering these elastic arteries exceeds that leaving them via the peripheral resistance, there is a net storage of blood in the aorta and large arteries during systole, which discharges during diastole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peripheral Resistance
Vascular resistance is the resistance that must be overcome for blood to flow through the circulatory system. The resistance offered by the systemic circulation is known as the systemic vascular resistance or may sometimes be called by another term total peripheral resistance, while the resistance caused by the pulmonary circulation is known as the pulmonary vascular resistance. Vasoconstriction (i.e., decrease in the diameter of arteries and arterioles) increases resistance, whereas vasodilation (increase in diameter) decreases resistance. Blood flow and cardiac output are related to blood pressure and inversely related to vascular resistance. Measurement The measurement of vascular resistance is challenging in most situations. The standard method is by the use of a Pulmonary artery catheter. This is common in ICU settings but impractical is most other settings. Units for measuring Units for measuring vascular resistance are dyn·s·cm−5, pascal seconds per cubic metre (Pa·s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otto Frank (physiologist)
Otto Frank (21 June 1865 – 12 November 1944) was a German medical doctor and physiologist who made contributions to cardiac physiology and cardiology. The Frank–Starling law of the heart is named after him and Ernest Starling. Family and early life (Friedrich Wilhelm Ferdinand) Otto Frank was born in Groß-Umstadt and was the son of Georg Frank (1838–1907), a doctor of medicine and a practicing physician, and Mathilde Lindenborn (1841–1906). Otto Frank was married to Theres Schuster in a Catholic wedding in Munich. Training and work Otto Frank studied medicine in Munich and Kiel between 1884 and 1889 (approbation in Munich 1889). During 1889 to 1891 he undertook training in mathematics, chemistry, physics, anatomy and zoology in Heidelberg, Glasgow, Munich and Straßburg. He then worked until 1894 as an assistant to Carl Friedrich Wilhelm Ludwig in the ''Physiologisches Institut'' in Leipzig. There in 1892 he completed his doctoral studies (''Promotion''). Subsequently ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fire Engine
A fire engine or fire truck (also spelled firetruck) is a vehicle, usually a specially designed or modified truck, that functions as a firefighting apparatus. The primary purposes of a fire engine include transporting firefighters and water to an incident as well as carrying equipment for firefighting operations in a fire drill. Some fire engines have specialized functions, such as wildfire suppression and aircraft rescue and firefighting, and may also carry equipment for technical rescue. Many fire engines are based on a commercial vehicle chassis that is further upgraded and customized for firefighting requirements. They are generally considered Emergency vehicle, emergency vehicles authorized to be Emergency vehicle equipment, equipped with Emergency vehicle lighting, emergency lights and Siren (alarm), sirens, as well as communication equipment such as two-way radios and mobile computer technology. The terms ''fire engine'' and ''fire truck'' are often used interchangeably ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephen Hales
Stephen Hales (17 September 16774 January 1761) was an English clergyman who made major contributions to a range of scientific fields including botany, pneumatic chemistry and physiology. He was the first person to measure blood pressure. He also invented several devices, including a ventilation (architecture), ventilator, a pneumatic trough and a surgical forceps for the removal of bladder stones. In addition to these achievements, he was a Philanthropy, philanthropist and wrote a popular tract on Alcohol intoxication, alcoholic intemperance. Life Stephen Hales was born in Bekesbourne, Kent, England. He was the sixth son of Thomas Hales, heir to Baronetcy of Beakesbourne and Brymore School, Brymore, and his wife, Mary (née Wood), and was one of twelve or possibly thirteen children.Clark-Kennedy, A. E. ''Stephen Hales, D.D., F.R.S.: An eighteenth century biography''. Cambridge University Press, 1929. Thomas Hales (died 1692) predeceased his father, Sir Robert Hales, 1st Baronet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giovanni Borelli
Giovanni Alfonso Borelli (; 28 January 1608 – 31 December 1679) was a Renaissance Italian physiologist, physicist, and mathematician who is often described as the father of biomechanics. He contributed to the modern principle of scientific investigation by continuing Galileo's practice of testing hypotheses against observation. Trained in mathematics, Borelli also made extensive studies of Jupiter's moons, the mechanics of animal locomotion and, in microscopy, of the constituents of blood. He also used microscopy to investigate the stomatal movement of plants, and undertook studies in medicine and geology. During his career, he enjoyed the patronage of Queen Christina of Sweden. He was the first scientist to explain that animal and human bodily movements are caused by muscular contractions. Biography Giovanni Borelli was born on 28 January 1608 in the district of Castel Nuovo, in Naples. He was the first-born son of Spanish infantryman Miguel Alfonso and a local woman named La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perfusion
Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ (anatomy), organ or a tissue (biology), tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion may also refer to fixation via perfusion, used in histological studies. Perfusion is measured as the rate at which blood is delivered to tissue, or volume of blood per unit time (blood volumetric flow rate, flow) per unit tissue mass. The SI unit is m3/(s·kg), although for human organs perfusion is typically reported in ml/min/g. The word is derived from the French verb ''perfuser'', meaning to "pour over or through". All animal tissues require an adequate blood supply for health and life. Poor perfusion (malperfusion), that is, ischemia, causes health problems, as seen in cardiovascular disease, including coronary artery disease, cerebrovascular disease, peripheral artery disease, and many other conditions. Tests verifying that adequate perfusion exists ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardiac Cycle
The cardiac cycle is the performance of the heart, human heart from the beginning of one heartbeat to the beginning of the next. It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following a period of robust contraction and pumping of blood, called systole. After emptying, the heart relaxes and expands to receive another influx of blood returning from the lungs and other systems of the body, before again contracting. Assuming a healthy heart and a typical rate of 70 to 75 beats per minute, each cardiac cycle, or heartbeat, takes about 0.8 second to complete the cycle. Duration of the cardiac cycle is inversely proportional to the heart rate. Description There are two atrium (heart), atrial and two ventricle (heart), ventricle chambers of the heart; they are paired as the heart#Left heart, left heart and the heart#Right heart, right heart—that is, the left atrium with the left ventricle, the right atrium with the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulse Pressure
Pulse pressure is the difference between systolic and diastolic blood pressure. It is measured in millimeters of mercury (mmHg). It represents the force that the heart generates each time it contracts. Healthy pulse pressure is around 40 mmHg. A pulse pressure that is consistently 60 mmHg or greater is likely to be associated with disease, and a pulse pressure of 50 mmHg or more increases the risk of cardiovascular disease. Pulse pressure is considered low if it is less than 25% of the systolic. (For example, if the systolic pressure is 120 mmHg, then the pulse pressure would be considered low if it were less than 30 mmHg, since 30 is 25% of 120.) A very low pulse pressure can be a symptom of disorders such as congestive heart failure. Calculation Pulse pressure is calculated as the difference between the systolic blood pressure and the diastolic blood pressure. The systemic pulse pressure is approximately proportional to stroke volume, or the amoun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Damping Ratio
In physical systems, damping is the loss of energy of an oscillating system by dissipation. Damping is an influence within or upon an oscillatory system that has the effect of reducing or preventing its oscillation. Examples of damping include viscous damping in a fluid (see Viscosity, viscous Drag (physics), drag), Friction, surface friction, radiation, Electrical resistance and conductance, resistance in electronic oscillators, and absorption and scattering of light in optical oscillators. Damping not based on energy loss can be important in other oscillating systems such as those that occur in ecology, biological systems and Bicycle_and_motorcycle_dynamics#Lateral_motion_theory, bikes (ex. Suspension (mechanics)). Damping is not to be confused with friction, which is a type of dissipative force acting on a system. Friction can cause or be a factor of damping. Many systems exhibit oscillatory behavior when they are disturbed from their position of static equilibrium. A mass su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydraulic Accumulator
A hydraulic accumulator is a pressure storage reservoir in which an Incompressible flow, incompressible hydraulic fluid is held under pressure that is applied by an external Prime mover (engine), source of mechanical energy. The external source can be an engine, a spring (device), spring, a raised weight, or a compressed gas.Although liquids are generally considered to be practically incompressible, gases may be compressed and this compressed gas is a convenient energy store. An accumulator enables a hydraulic system to cope with extremes of demand using a less powerful pump, to respond more quickly to a temporary demand, and to smooth out pulsations. It is a type of energy storage device. Compressed gas accumulators, also called hydro-pneumatic accumulators, are by far the most common type. Types of accumulator Towers The first accumulators for William Armstrong, 1st Baron Armstrong, William Armstrong's hydraulic dock machinery were simple raised water towers. Water was pumped ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
