Effects of microgravity on microcirculation.

The blood behaviour in human circulatory system observed during space flights reveals that the microgravity environment reduces the flow rate and increases the haematocrit compared with the situation on the earth surface. The present study gives a theoretical analysis of the above phenomena by considering a two layer Newtonian model for blood flow in capillaries. The effect of gravity on plasma layer as well as on the blood viscosity is taken into account for calculating the percentage change in flow rate of blood. The corresponding apparent viscosities on the earth surface and in space are estimated. The results are analyzed and presented graphically. The findings agree reasonably well with the data observed in spaceflight experiments.