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81 Cards in this Set
 Front
 Back
Power is

the rate energy is transferred. describes how fast work is being done
Watts=Joules/sec 

Work is

the amount of energy that is transferred, integrates total power used to complete job over time
Work = avg power x total time Joules= Joules/ sec x seconds 

Energy

has multiple physical forms such as
potential kinetic heat radiation units vary on which type of energy used 

conservation of energy

fundamental law stating that energy is never lost, only converted to another form


potential energy is

energy that is stored and can be converted to another form of energy


kinetic energy is

energy in motion and is proportional to the velocity squared of the movement


pressure is

the measure of force per unit of area
two categories: Static pressure (potential energy) Dynamic pressure (kinetic energy) 

flow (volumetric) is

the volume of fluid per time that moves past a point
liters/min meters cubed/sec 

resistance is

the ratio of pressure drop across a flow path per volumetric flow
measure of the impediment which is overcome for flow to occur 

capacitance is

the measure of the ability to hold a change in volume per change in time
change in V / change in t 

compliance is

the ratio of the change in volume to a change in pressure
dV/dP 

Velocity is

the speed that a fluid moves in a specific direction
units of distance/time m/sec cm/sec 

viscosity (fluid) is

the ratio of shear stress to the shear rate of a fluid
measure of the resistance of a fluid to flow due to the attraction of molecules 

In hemodynamics the driving force that propels blood is a

change in energy
it travels from areas of high energy to those of low energy 

when considering the law of conservation energy can be divided into two categories of

potential and kinetic energy


The law of conservation makes it so that there is only a conversion back and forth between

kinetic and potential energies


the pressure that represents the force exerted on the vessel walls represents

potential energy


the force in the direction of flow represents .... which is related to the velocity of the blood

kinetic energy


hydrostatic pressure is

potential energy related to the weight of a column of fluid above a reference point secondary to gravity


the equation for hydrostatic pressure is

ro x g x h


in the hydrostatic pressure equation h means

the height of the column


in the hydrostatic pressure equation ro means

density


in the hydrostatic pressure equation g means

gravity


hydrostatic pressure is proportional to the

height of the column, and density of the material


clinically hydrostatic pressure is related to the ___ and ___ of the patient

height, position


what is the hydrostatic pressure in the body?

2mmHg/inch


In volumetric flow Q means

volumetric flow


in fluid dynamics v is

velocity


high flow does/ doesn't correlate to a high velocity

doesn't


High compliance infers that there is a large increase in ___ with small change in ___

volume, pressure


fluid viscosity is defined as

the ratio of the shear stress to the shear rate
a measure of the resistance to flow offered by a fluid / molecule stickiness 

fluid viscosity is ___ dependent

heat


resistance to flow is ___ to the viscosity of the fluid

proportional


for the same radius and the same volumetric flow, if the length increases the resistance ____

increases


resistance is ____ to length

proportional


resistance is ____ to 1/radius

proportional


for the same length, if the radius increases the resistance ___

decreases


which has a greater impact on resistance? length or radius

radius


resistance is ____ to 1/radius^4

proportional


a higher viscosity results in a ____ resistance to flow

higher


what is the resistance equation

R = (8 x length x viscosity) / (pi x radius^4)


for the same velocity a larger CSA ____ volumetric flow

increases


Q is ____ to area

proportional


area is equated as

radius squared


for the same CSA a higher average velocity ____ the volumetric flow

increases


Q is ____ mean spatial velocity

proportional


the contiunity equation states that

flow through one region must equal all the other flow through any other reigion in the flow system


what is the continuity equation

Q = mean spatial velocity x area


a v with a line over it represents

mean spatial velocity


change in P (pressure) is ____ to R (resistance)

proportional


the smaller radius of pipeline B results in a ____ pressure gradient for hte same volumetric lower as pipeline A

higher


change in pressure is ____ to Q

proportional


what is a Newtonian fluid

the viscosity of the fluid only changes with temp


is blood a newtonian fluid

no


What assumptions are made to us poiseuille's law

flow conduit is a rigid cylindrical tube
flow is stead, stable, laminar flow fluid is newtonian 

when is poiseuille's law applicable?

when the hemodynamic state is such that error caused by incorrect assumptions is small enough that the law is good enough to predict behavior


Bernoulli's equation says that

for a closed loop system, all the energy at one point must equal all the energy at another point


to use the simplified Bernoulli's equation we need to assume that

blood is flowing through a rigid tube
blood is a nonviscous fluid no friction surface occurs blood is an incompressible homogenous fluid an blood is in laminar flow 

steady flow is

constant volumetric flow


pulsatile flow is

fluid which moves in a well behaved manner and uniform direction
will move in concentric rings not crossing boundaries 

plug flow is

a velocity profile that is relatively consistent across the vessel


parabolic flow is

a laminar flow profile which mimics a parabola
normal arterial blood flow in a straight, undiseased segment 

disturbed flow

any deviation from laminar flow


turbulent flow is

when fluid does not move in a well behaved manner
chaotic or random flow 

acceleration is

change of velocity over time
positive 

entrance effect

change in velocity profile which happens when entering a vessel of reduced diameter


exit effect

change in velocity profile which results when exiting from a vessel of smaller diameter
the inertial energy is dissipated by turbulent flow 

Raynolds number is

a dimensionless index that indicates the occurrence of turbulent flow


the higher the reynolds number the ____ the likelihood of turbulence occuring

greater


reynolds number is a ratio between the ____ forces and the ____ forces

inertial, viscous


What is reynolds ratio

R = intertial forces / viscous forces


What is reynolds ratio equation

R = (ro x d x v) / (nu)


reynolds number when it is _______ usually results in turbulence

>2000


Explain the normal pressure waveform in the aorta

a rapid systolic upstroke followed by a gradual decrease to the dicrotic (compliance) notch, followed by the gradual decline in pressure throughout diastole


atheroscelrotic arteries will / will not have a dicrotic notch?

will not


capacitance allows energy to be stored in the walls of the aorta to provide

energy to propel blood during diastole


when pressure is applied to an elastic vessel wall, it stretches in a

radial direction, causing an overall increase in CSA over the length of the vessel


compliant vessels cause a fallacy in poiseuille's law assumption because

the compliant vessels create a much faster increase in volume with respect to pressure than the law predicts, causing a non linear relationship change between pressure and volume


how much blood is held in the venous system at rest?

65%


what allows for the venous system to act as a reservoir

it's capacitance


where does blood also reservoir at rest?

skin and liver
