Below are two vessels shown. Assuming the pressure along both the vessels is the same and both of them follow linear flow pattern. What will the amount of blood flow in A compared to B
Ans. (c) 8 times(Ref: Ganong, 25th ed/p.573)Blood flow (F) inside vessel depends on:Pressure difference (PA -PB ) - directly relatedViscosity of the fluid (e) - inversely related#Viscosity is a measure of a fluid's resistance to flow#A fluid with low viscosity flows easily. Such fluids are called Newtonian fluid. Example is water#A fluid with high viscosity flows resists motion. Such fluids are called Non-newtonian fluid. Example is blood#Fahraeus-Lindqvist effect: This effect is seen mainly in capillaries where RBCs flow in the center which leaves cell free plasma near the vessel wall. So, the viscosity change per unit change in hematocrit is much less in capillariesRadius of the vessel (r4) - directly relatedLength of the vessel (L) - inversely relatedInterrelation of these factors are expressed in Poiseuille- Hagen formula which is:F=(PA -PB )*pr4/8eL#Since, length is doubled and diameter is doubled in vessel A, its flow will be:F=24/2=16/2=8 times
32 times
16 times
8 times
4 times
Heart, Circulation, and Blood