层流( l aminar flow):血液中每个质 点的流动方向一致。但各质点的流速 不同 湍流( turbulent flow):血液中 各个质点的流动方向不一致 regular Vortices 血流速度快,血管口径大,血液粘滞 低时易产生湍流。 FIGURE 20-2. A, In laminar flow, all elements of the fluid move in streamlines that are parallel to the axis of the ube: no fluid moves in a radial or circumferential direc tion, B, In turbulent flow, various elements of the fluid move irregularly in axial, radial, and circumferential directions层流（laminar flow)：血液中每个质 点的流动方向一致。但各质点的流速 不同. 湍流（turbulent flow)：血液中 各个质点的流动方向不一致. 血流速度快，血管口径大，血液粘滞 低时易产生湍流