血液の流動的性質 : 生物のレオロジー
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概要
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The following conditions that affect the flow properties of blood are discussed in brief from the rheological point of view. (1) Volume fraction of erythrocytes-hematocrit value- The simple Einstein relation between relative viscosity and volume concentration of suspended particles is not valid for blood. The observed relative viscosity is greater than that calculated, owing to the interaction between the erythrocytes and a increase in the effective hematocrit value produced by enclosing and immobilizing of a certain amount of plasma within the collided erythrocytes groups. The asymptotic minimum viscosity of blood is given by a modified Hatschek's equation, over a wide range of hematocrit values. (2) Temperature : - The relative viscosity of a disperse system should not be affected by temperature unless the volume fraction and the shape of the dissolved or suspended particle changes. The relative viscosity of blood is, however, affected by temperature. It rises by about 10 per cent by decrease in temperature from 37℃ to 17℃. This rise is considered to be due to a small increase in the volume of individual erythrocytes, together with a change of shape towards a more spherical and less disc-like form. (3) Perfusion pressure : - If the perfusion pressure head is sufficiently large, the rate of flow of blood through a rigid vessel increases in proportion to the increase in the applied pressure head. As the pressure head is lowered, the plotted points indicating the relation between the rate of flow and the applied pressure lie on a smooth curve, which is convex to the pressure axis.The convexily becomes more and more prominent with decrease in the pressure head. Blood, therefore, is not a Newtonian fluid. It will appear to behave as Newtonian fluid only in limiting conditions in which the mean shearing stress are rate of shear-the following factors should be taken into account.
- 社団法人日本材料学会の論文
- 1964-05-15