ABSTRACT
Red blood cells (RBCs) perform a vital function in any higher organism by delivering oxygen to tissue cells, while platelets are essential to stop bleeding in case of vessel injuries. The final component of mechanical resistance described herein is again related to the lipid bilayer. The RBC membrane is about 100-nm thick, and its mechanics is determined by two essential components: the lipid bilayer and the spectrin network. If an RBC suspension containing rouleaux is driven through a blood vessel or microchannel at low flow speeds, the rouleaux are strong enough to withstand shearing forces and thus remain largely intact. The formation of rouleaux is physiologically relevant, as it strongly affects blood viscosity at low shear rates. If a suspension of RBCs in plasma is standing quietly or flowing at very low speeds through a channel, one can observe that RBCs spontaneously start to form well-ordered stacks.
