205textnotes27 - 2- P 1 (Fig. 14-4) in a system with...

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Transport: oxygen to cells, removes cellular wastes for excretion cell to cell communication important role with the immune system A.2 Structure : includes blood vessels (systemic and pulmonary systems) and heart. Figure 14-1 At any given time only 5% of the blood volume is in the capillaries performing the ultimate function of the cardiovascular system. B. Pressure, Volume, Flow, and Resistance B.1 Pressure (P), Volume (V), Flow (Q) and Resistance (R) : Pressure decreases as blood moves from the aorta through the capillaries to the venae cavae. Units: Pressure (mmHg), Volume (L), Flow (L/min), Resistance when volume decreases, pressure increases. The contraction of the ventricles produces an increase in pressure which causes the flow of blood (driving pressure) liquids and gases flow down pressure gradients: Q is proportional to delta P; where delta P = P
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Unformatted text preview: 2- P 1 (Fig. 14-4) in a system with resistance, such as the cardiovascular system, pressure drops along the same direction as the flow Figs. 14-2, 14-3 . 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. 14-5) 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. 14-6 With constant flow, velocity changes inversely with the radius of the tube. -------------------------------------------------------- C. Structure of the Heart -------------------------------------------------------- C.1. STRUCTURE:...
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