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Multidisciplinary Senior Design I TEAK – Bioengineering Biomedical Engineering: The Circulatory and Respiratory Kit Instructor Preparation Guide: Blood Vessel Activity Bioengineering Overview Bioengineering is the application of engineering principles to address challenges in the fields of biology and medicine. Bioengineering applies the principles of engineering design to the full spectrum of living systems. Circulatory System Overview The main components of the human circulatory system are the heart, blood, and the blood vessels which carry blood through the rest of the body. These three components, the heart, blood, and blood vessels form what is known as the cardiovascular system. The circulatory system includes two loops throughout the body know as the pulmonary circulation loop and the systemic circulation loop. The pulmonary circulation loop is the loop in which the blood becomes oxygenated while the systemic circulation loop is the loop in which provides the oxygen rich blood to the rest of the body. Figure 1.0 - The Human Circulatory System 1 Figure 1.1 – Clogged Blood Vessel Blood vessels are the part of the circulatory system that transports blood throughout the body. Blood vessels become clogged when a build of waste known as plaque builds up on the interior walls of the blood vessels. Composed of fats, cholesterol, calcium, and other blood cell waste, the build up of plaque causes the heart to work harder due to the increase in resistance to flow through the blood vessel. Typical results of clogged blood vessels are heart attack, stroke, and arrhythmia (irregular heart beat). In order to reduce the risk of heart attack and stroke due to clogged blood vessels, biomedical engineers and doctors have designed devices such as stents, balloon catheters, and catheters to open clogged blood vessels and allow for normal flow conditions to resume. Figure 1.2 Balloon Catheter Applications 2 Blood Vessel Flow Characterization Overview The flow of fluid particles can be described as either turbulent or laminar flow. Laminar flow is flow in which the fluid particles move in smooth layers, or laminas. Turbulent flow is flow in which the particles rapidly mix as they move along due to random three dimensional velocity fluctuations. Flow within a blood vessel is characterized as turbulent flow. Though turbulent flow is not ideal for most practical applications, it is desirable for blood flow because the random mixing allows for all of the blood cells to contact the walls of the blood vessels to exchange oxygen and other nutrients. Flow can be characterized as either laminar or turbulent through the evaluation of the Reynolds Number for the given flow conditions. Reynolds Number is calculated by the equation: ρ VD Re = µ Where: ρ = fluid density V = fluid velocity D = Diameter µ = kinematic viscosity For most applications, if the Reynolds Number is greater than 2300, flow is characterized as turbulent. If the Reynolds Number is less than 2300, flow is characterized as laminar. Figure 2.0 – Turbulent vs. Laminar Flow 3 Resources • • Introduction to Fluid Mechanics. 6th Edition. Fox, McDonald, Pritchard. www.wikipedia.com Image Resources • Figure 1.0: http://gonatural.com.ph/herbalblog/wpcontent/uploads/2007/07/Circulatory%20system.jpg Date: January 29, 2009 Time: 9:48 pm • Figure 1.1: http://images.google.com/imgres?imgurl=http://www.biotechweblog.com/50226711/images/atherosclerosis.jpg&imgrefurl=http://www.agorav ox.com/article.php3%3Fid_article%3D4888&usg=__fHScGPEoARdANkr2qIXN PyLb5Wk=&h=200&w=250&sz=10&hl=en&start=1&tbnid=dStyit3sgN5bkM:& tbnh=89&tbnw=111&prev=/images%3Fq%3Dclogged%2Bblood%2Bvessel%26 gbv%3D2%26hl%3Den%26sa%3DG Date: January 29, 2009 Time: 9:48 pm • Figure 1.2: http://www.heart-stint.com/images/angio1a.gif Date: January 31, 2009 Time: 2:38 pm • Figure 2.0: http://www.cheng.cam.ac.uk/research/groups/electrochem/JAVA/electrochemistr y/ELEC/l2fig/laminar.gif Date: January 29, 2009 Time: 9:48 pm 4