Erasistratus's Model Of Respiration

Erasistratus’s model of the respiration and blood distribution is considerably more mechanical than Aristotle’s due to the technological advances that were thriving in Alexandria compared to Athens. Both scientists base their models of respiration and blood distribution in the body from technological-ladenness of observation. Erasistratus proposes that heart uses force propulsion to distribute air and blood throughout the arteries and veins. His concept focuses on “the filling towards what is being” emptied, making the body a quasi-pneumatic machine. Erasistratus believes that blood and air distribution underwent a unidirectional flow (rather than a circulatory one). His model has its roots in the mechanism that drove Ctesibius’ force pump,
Similarly, Erasistratus postulates “that by turning from the inside outwards, (blood) open the mouths of the vessels because of the matter flowing out, whenever the heart distributes matter, but for the rest of the time they close the mouths tightly and prevent any of what has been pushed out form flowing back in (Galen, De plac. Hipp. Et. Plat. 6.6.11-12). The mouths of the vessels are equivalent to the valves in the force pump. They regulate the direction of flow of the fluid and ensure that the system remains pressurized. Aristotle on the other hand, was not exposed to such technological advancements in Athens. Rather he relies on analogies and understandings of thermodynamics to support his model. He uses the analogy of boiling water to describe the beating of the heart. He says that when water is heated it increases in size, “but in the heart the liquid flowing in from nourishment expands because of heat and causes pulsing whenever the expansion increases to the furthest membrane of the heart” (Aristotle, On Respiration,