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Unformatted text preview: 2 P 1 (Fig. 144) in a system with resistance, such as the cardiovascular system, pressure drops along the same direction as the flow Figs. 142, 143 . resistance opposes flow: (similar to ohm's law V = IR for electric currents) delta P = QR or Q = delta P / R Poiseuille's Law (Flow of a viscous fluid) (Fig. 145) Q = ( pi r 4 delta P) / (8 eta l) Where: l is the length of the tube; r is the radius; and, eta is the viscosity of the fluid Since Q = delta P / R, then (1/R) = ( pi r 4 ) / (8 eta l) and therefore R = (8 eta l) / ( pi r 4 ) R is proportional to 1/r 4 Flow rate vs. velocity of flow : Fig. 146 With constant flow, velocity changes inversely with the radius of the tube.  C. Structure of the Heart  C.1. STRUCTURE:...
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 Fall '09
 Blaber

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