ABSTRACT
As dictated by biologic principles, once an aerobic organism’s total cell mass is large enough that simple diusion from the environment cannot provide the necessary components for cellular metabolism, a circulatory system is required. If you were to take a moment and try to design a circulatory system of your own, you will begin to realize that certain components are required. As the majority of cells in an organism nd themselves in an aqueous environment, the most ecient design of a circulatory system is to provide bulk transport through ow of an aqueous solution. Most importantly, this circulatory system must provide bulk transport of required components of cellular metabolism and a means for the cell to expel toxic by-products. is bulk transport of metabolites must occur at a rate greater than or equal to the rate of cellular metabolism. In animals, the perfusion solution blood uses the basic chemical properties of iron in the form of hemoglobin to increase the capacity at which oxygen can be transported. By increasing the eciency of the metabolitecarrying capacity, the ow rate of the blood is decreased so that the cells circulating in the blood are not destroyed by the forces within the blood vessel.
