bfood through the capillarines it was GHL Hagen, a contemporafy of Poisuille who worked furtner with the problem and found out the mathematical expres

tadeed, AC Burton onc e thmarked that. most of the (Hagen-Poiseuille} Jaw is common sense'l Hagen - Poiseuille law is also known. simply. as Poiseuille's (pronounced. Pawazee, -law Jean Leonard Marie Poiseuille was a Paris based physicioan and physicist who., in 1842, grasped the fundamental principles äs descnbed above in connection with his researches on flow of bfood through the capillarines it was GHL Hagen, a contemporafy of Poisuille who worked furtner with the problem and found out the mathematical expres sion It is emphasized, that only, a Newtonan fluid passing ihrough a rigid lube obeys the Hagen Potisuille's law Blood, stnctly epeaking, is not a Newtonian fluid. also blood vesels are not rigid tubes Nevertheless. Hagen Poiseuille's law gives an idea about the major' determing factors of flow Resistance against the fIow As the blood flows onwards, it faces a 'resislance1 againsl the flov- The resistance has to be overcome othe rwise flow will stop However. in ovetcoming resistance, the flowing blood also loses some öf its. energy (wthich it received ftom the heart because öf the ventncutar contraction) This loss of total energy me ans that the lateral pressure is also falling (see Bemoulli's ptinciple. earlier in this chapter As the resistance is,offered by the vascular tree, which lies peripheral to heart. this is also called ths peripheral resistance The interrelationship between the volume of blood fowing per unit time O the resistance, R, the pressure gradient, , in the Hagen • Poiseulie iaw) is given by the expression [The value of R. there fore is. putting values ofO