22.23. Fluid flow, diffusion Flashcards by Ines Crawford

Viscosity formula

η=t/D
t : sheer stress F/A
D : velocity gradient dV/dy

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Viscosity of distilled water

1mPa*s

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What is dynamic pressure?

1/2rho*v²

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What is hydrostatic pressure?

rhogh

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Bernoulli’s law equation

[1/2rhov²]+[rhog*h]+pstat = CST

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Stokes law

F = 6piηrv
F : stokes drag, frictional force
v : flow rate

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Stokes coefficient

Measure of the frag of an object in a moving fluid.

F = gamma * v

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Average blood viscosity

5mPa*s

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What is the normal range of hematocrit

40-50%

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High-molecular weight proteins in plasma

Immunoglobulins, fibrinogen

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Mean free path equation

L = v * τ
v : velocity
τ : average time between collisions

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Diffusion constant equation

D = (v*L)/3

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Mean speed of particles

vmean = sqrt [(3kT)/m]

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Equation of mobility

u = vdrift / E
u = vdrift / (f/q)

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Unit of diffusion coefficient?

m²/s

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Unit of matter flow density (flux)

mol/(m²*s)

Unit of matter flow rate

mol/s

Flow density and flow rate relation

Jv = Iv/A

PC02 and PO2 in alveoli

PCO2 : 40 mmHg

P02 : 100 mmHG

PCO2 and P02 in cell

PCO2 : 46 mmHg

P02 : 40 mmHg

Osmotic pressure

Hydrostatic pressure which needs to be applied to a solution to prevent inwards flow of its pure solvent across a semipermeable mb

Osmotic pressure formula

pi = iMR*T
i : vanthoff factor
M : molar concentration (mol/L)

What are streamlines?

They characterize the direction of motion

- The denser the lines, the greater the speed

What does viscosity characterize?

It characterizes the internal friction of fluids and gases

What causes viscosity?

resistance of fluid to inner interactions (gas have low interactions bw molecules)

What is sheer stress?

force tending to cause deformation of a material by slippage along a plane (parallel)

What are 4 main characteristics of an ideal fluid?

1. No viscosity 2. Doesn't experience sheer stress 3. Constant density 4. Incompressible

What is Bernoulli’s law?

in a stationary flow of an ideal fluid, the sum of all forms of energy along a streamline is the same at all points on that streamline

What is plasma skimming?

natural separation of RBC from plasma at bifurcations - makes hematocrit of capillaries lower than that of arteries

What is shear rate?

Shear rate is the rate of change of velocity at which one layer of fluid passes over an adjacent layer (velocity gradient)

What is Newton's law of friction?

sheer stress between adjacent fluid layers is proportional to the velocity gradient difference between the 2 layers

What are the 6 main determinants of blood viscosity?

1. Hematocrit 2. Plasma viscosity 3. Plasticity of RBC 4. Aggregation of RBC 5. Flow rate, velocity gradient 6. Blood vessel diameter

What is the random walk of particles?

- Path of particles is a succession of random steps | - the particle travels a R(t) net distance from its original position in t time

What are the 4 parameters used to describe transport of matter?

1. Mean free path (average displacement) 2. Drift speed 3. Mobility 4. Diffusion coefficient

What is diffusion?

change in spatial distribution of particles because of random thermal motion

On what 4 factors does heat conduction depend?

1. temperature gradient 2. cross section of the materials involved 3. material length 4. Properties of the material

What is osmosis?

molecules of SOLVENT diffusing across partially permeable membrane from a less concentrated solution to a more concentrated one

What is osmolarity?

The concentration of a solution needed to keep balance with a heterogenous solution