A simple model of capillary-tissue fluid exchange system is developed with particular emphasis on the permeability properties of the blood vessel based on Starling's law. Inertia effects have been neglected in comparison to viscous effects because of low Reynolds number blood flow in capillary. Capillary blood vessel is approximated by circular cylindrical tube with permeable wall. Introducing three layered model for blood with central core region, flow region with Casson fluid surrounded by a peripheral layer of viscous fluid so as to represent a cell free region near the wall and a thickly concentrated plug region due to the cell migration towards the central line. If the net flow of suspending medium filtered is zero then the total amount of plasma entering from capillary into the tissue and re-absorbing back into the capillary are equal. If it is positive, the fluid in excess into the tissue leaks into the lymphatic vessel to join back with main arterial blood flow and removal of separated waste products through veins and spleen. Thus, Lymphatic flow plays an important role in protecting the tissue from edema and dehydration.