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Blood viscosity is a measure of the resistance of blood to flow. It can also be described as the thickness and stickiness of blood. This biophysical property makes it a critical determinant of friction against the vessel walls, the rate of venous return, the work required for the heart to pump blood, and how much oxygen is transported to tissues and organs.
Typical values for the viscosity of normal human plasma at 37 °C is 1.4 mN·s/m 2. [3] The viscosity of normal plasma varies with temperature in the same way as does that of its solvent water [4];a 3°C change in temperature in the physiological range (36.5°C to 39.5°C)reduces plasma viscosity by about 10%. [5]
Turbulent flow is present in circumstances under which Re > 4000. The range of 2000 < Re < 4000 is known as the transition range. Most blood flow in humans is laminar, having a Re of 300 or less, it is possible for turbulence to occur at very high flow rates in the descending aorta, for example, in highly conditioned athletes.
For a compressible fluid in a tube the volumetric flow rate Q(x) and the axial velocity are not constant along the tube; but the mass flow rate is constant along the tube length. The volumetric flow rate is usually expressed at the outlet pressure. As fluid is compressed or expanded, work is done and the fluid is heated or cooled.
In fluid dynamics, the Hagen–Poiseuille equation is a physical law that gives the pressure drop in a fluid flowing through a long cylindrical pipe. The assumptions of the equation are that the flow is laminar viscous and incompressible and the flow is through a constant circular cross-section that is substantially longer than its diameter.
Viscosity of the membrane can affect the rotation and diffusion of proteins and other bio-molecules within the membrane, there-by affecting the functions of these things. [1] Membrane fluidity is affected by fatty acids. More specifically, whether the fatty acids are saturated or unsaturated has an effect on membrane fluidity.
Below are several examples of differing types of local blood flow regulation by specific organ type or organ system. In each case, there is a specific type of intrinsic regulation occurring in order to maintain or alter blood flow to that given organ alone, instead of creating a systemic change that would affect the entire body.
The Fåhræus–Lindqvist effect (/ f ɑː ˈ r eɪ. ə s ˈ l ɪ n d k v ɪ s t /) or sigma effect [1] describes how the viscosity of blood changes with the diameter of the vessel it travels through. In particular there is a decrease in viscosity as the vessel diameter decreases, but only at small diameters of 10–300 micrometers (mainly ...