1 2 2=n1 Q= 10 ml/sec Q2=5mL/sec O3=160 mL/sec Ga=5mU/sec A FIGURE 20-4. The flow, Q, of fluid through a tube is inversely proportional to the length, L, and the viscosity, n, and directly proportional to the fourth power of the radius, r. A, Reference condition: for a given pressure, length, radius, and viscosity, let the flow Q, equal 10 mL/sec. B, If the tube length doubles, flow decreases by 50%. C, If the tube radius doubles, flow increases 16-fold. D, If viscosity doubles, flow decreases by 50% 影响因素: 1.血管口径:口径↑,阻力↓,血流量↑; 2.血液粘滞度:粘滞度↑,阻力↑,血流量↓影响因素: 1.血管口径: 口径↑，阻力↓，血流量↑ ； 2.血液粘滞度: 粘滞度↑，阻力↑ ，血流量↓