FLUIDS and FLOW-CH5 Flashcards

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1
Q

Fluids is a term used to describe

A

Liquid or gas

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2
Q

Important characteristic of fluids and gases

A

Flow

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3
Q

Hydrostatic

A

study fluids are not moving

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4
Q

Hydrodynamics

A

fluids in motion

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5
Q

Both hydrostatic and hydrodynamics involve

A

pressure and density

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6
Q

Pressure in a liquid is calculated using

A

density and height of the fluid

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7
Q

P in a liquid formula:

A

dhg (pressure = density * height*gravity )

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8
Q

To include pressure exerting force on the liquid’s surface, simply add it to equation
P2 is the ________ and P1 is the

A

P2 = P1 + dhg

pressure in the liquid; pressure of the gas added.

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9
Q

Calculate the pressure of a depth of 1000m below the surface on the ocean. Density is 1.03x10^3. 1 atm = 101325

A

P2 =P1 +dhg

P2= 1.07 x10^7

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10
Q

Definition of flow

A

Quantity of fluid passing a point per unit of time

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11
Q

Flow (definition formula)

A

V / t

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12
Q

Pressure =

relating to flow

A

F x R
P= pressure
F= Flow
R= Resistance

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13
Q

Change in flow written as

A

Q= QDot

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14
Q

2 types of flow

A

Laminar flow

Turbulent flow

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15
Q

Laminar flow most important factor : Remember mnemonic:

A

VISCOSITY

LVS

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16
Q

Laminar flow reynolds number:

A

<2000

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17
Q

Turbulent Flow Reynolds number

A

Reynolds >3000

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18
Q

Turbulent flow most important factor

A

Density

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19
Q

Molecules close in the center moving faster in (because of drag)

A

Laminar

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20
Q

Turbulent flow has a

A

continuous varying pattern of flow , chaotic and abruptly changing.

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21
Q

Best way to measure flow

A

POUISELLE”S LAW

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22
Q

What POUISELLE”S LAW

A

Flow = P /R

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23
Q

Turbulent flow occurs at _____velocity

A

High

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24
Q

Bigger factor for turbulent flow

A

density

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25
Q

Viscosity represented by and is defined as __________

A

n; Viscosity is the resistance a fluid offers to the motion of a solid through it

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26
Q

POUISEILLE’s LAW (KNOW THIS )

A

F = Pir^4 change P/ 8 nl

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27
Q

Resistance to flow

A

R = 8nl/Pi r^4

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28
Q

Pouiseille’s Law

A
F flow in L/s
n= viscosity in Pa/s
P= Pressure in pascals
r= radius 
l= length
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29
Q

Double length

A

Flow in half

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30
Q

Biggest factors that affect vessel

A

Radius of vessel

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31
Q

Radius increase by

A

area changes power of 4

Volume increases by power of 8

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32
Q

Calculate aortic blood flow

A

Blood viscosity = 0.0015Pas. Pressure of 13000pa, is applied r=0.0010 ; l= 1.0
F= 3.4 x 10 ^-2 m^3/s

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33
Q

Pouiselle’s law : Arterial occlusion

A

A small amount of arterial occlusion can have a surprisingly large effect.

34
Q

A _____decrease in radius will halve the volume flow rate

A

19%

35
Q

According to poiseuille’s law

A

a five fold increase in BP would be required if the increase were supplied by blood pressure alone.

36
Q

a ____% dilation of resistance in vessel

A

50

37
Q

Since the ______Vessels provide most of the resistance to flow, the ______In their position just prior to the capillaries can promise a major controlling influence the volume flow rate

A

Smaller; arterioles.

38
Q

first: Flow is _____ ____ to the_______difference and to the ______power of the radius

A

Directly proportional; pressure; radius

39
Q

If pressure goes up , the flow

A

Increases

40
Q

2nd: Flow is ______ _______ to viscosity and length

A

Inversely proportionate

41
Q

Finally, Viscosity only affect

A

laminar

42
Q

Bernoulli’s Principe

A

For a non-compressible, non-viscous fluid undergoing LAMINAR FLOW

43
Q

Bernoulli’s Principe

A

For a non-compressible, non-viscous fluid undergoing LAMINAR FLOW, the sum of the pressure, kinetic and potential energies per unit volume remains a constant at all points along the line flow.

44
Q

What is the pressure differential accross a flow roof having an area of 240m^2 when the wing blow at 25m/s the density of air is 1.29kg/m^3 (assume the speed of air inside is 0)
Change in P =
F=P*A

A

403Pa

1/2 (V2^2 - V1^2)
F 96700N or 10.9 Tons

45
Q

Faster air move

A

Less pressure there is

46
Q

Fick’s Principle

A

Vo2 = Co x (aCO2 - vO2)

47
Q

Fick’s Principle (43)

A

Vo2 = CO x (aCO2 - vO2)

48
Q

PRESSURE IS DEFINED AS A ________

A

FORCE OVER AREA (m^2)

49
Q

Pascal’s principle is

A

Force in/ Area in = Force out / Area out

50
Q

Flow SI units

A

m^3/s

51
Q

As the diameter of the tube decreases, the speed of the fluid

A

decreases.

52
Q

The velocity of a fluid running through a pipe is _______to the area
Area1 x velocity 1 = Area 2 x velocity 2

A

INVERSELY PROPORTIONAL to the area

53
Q

We can also calculate pressure in a liquid at any depth if we know

A

the density of the liquid.

54
Q

In an open system P1 would simply be __________

A

1 atmosphere)

55
Q

Mnemonic: TD (touch down) =

A

Turbulence is Density dependent

56
Q

Reynold’s number attempts to

A

describe the point at which flow changes from laminar to turbulent, and the
spectrum in-between.

57
Q

Turbulent flow is

A

Nonlinear relationship of pressure and flow during turbulent flow

58
Q

Flow varies ______ with the viscosity (thickness) of a fluid

A

inversely

59
Q

Increased Hct = viscosity = resistance = blood flow

A

increase viscosity
increase resistance
decreased blood flow

60
Q

Increased Hct secondary to certain conditions:

A

dehydration, cyanotic congenital heart disease, polycythemia)

61
Q

Changes in Pressure are________

Changes in viscosity or length are________

A

directly proportional

inversely proportional

62
Q

Poiseuille’s law for anesthesia

A

A small amount of arterial occlusion can have a large effect

63
Q

The radius component also explains why an 18G cannula

A

has less flow (105 ml/min) than a 16G (220 ml/min)

64
Q

Secondly, flow is inversely proportional to _________ and ______Lastly look at the flow rate recorded on a shorter 18G I.V. cannula and compare it with the longer 18G on a 15cm CVP line. The shorter cannula has

A

viscosity and length; a greater flow rate despite the two having then same radius.

65
Q

The density of the fluid only comes into play when________

A

flow is turbulent.

66
Q

Occlusion is 0% if pressure is 120mmHg Flow rate is _______pressure to restore normal flow rate is ______

A

100cm^3 ; 120mmHg

67
Q

Occlusion is 20% if pressure is 120mmHg Flow rate is _______pressure to restore normal flow rate is ______

A

41cm^3; 293 mmHg

68
Q

Occlusion is 50% if pressure is 120mmHg Flow rate is _______pressure to restore normal flow rate is ______

A

6.3cm^3;

69
Q

Occlusion is 80% if pressure is 120mmHg Flow rate is _______pressure to restore normal flow rate is ______

A

0.16cm^3; 75,000mmHg

70
Q

DO2= Delivery of oxygen equation

A

(HR x SV) x (1.34 x [Hgb] x SaO2) + (0.003 x PO2)

71
Q

Blood Flow = Rate of uptake or excretion

arterial – venous concentration

A

Rate of uptake or excretion / arterial – venous concentration

72
Q

Fick Principle Different than ________

A

Fick’s Law of Diffusion

73
Q

Bernouilli’s principle
Total energy = ____ + _____
Total energy is ______ at all points in the streamline
As kinetic energy increases potential energy must decrease
A1V1 = A2V2

A

PE + KE
the same
decrease

74
Q

If the cross sectional area is reduced, the velocity is

A

increased.

75
Q

Describe viscocity and how it is measured?

A

Viscosity is the resistance of a fluid to flow

76
Q

Fluid with high viscosity

A

Do not readily flow

77
Q

Viscosity can be determined by measuring the

A

amount of time it takes for a fluid to flow a known length through a tube of known diameter

78
Q

Describe how poiseuille’s law theorem relates fluid to viscosity and tube size

A

The flow rate of a fluid through a tube is directly proportional to the radius of the tube raised to the FOURTH POWER. In addition, the flow rate is inversely proportional to the viscosity (n) of the fluid and the length of the tube through which the fluid flows.

79
Q

Flow rate is V/T =

A

(P1-P2) Pi r^4 / 8nL

80
Q

Explain why moving an IV bag higher above the patient results in flow rate of the IVF

A

The pressure at the needed (P2) is related to the pressure of the fluid in the IV bag (P1) plus the product of the density of the IV fluid, the acceleration due to gravity and the height of the IV bag above the needle. The pressure of the fluid at the needle can thus be readily increased by simply raising the height of the IV bag above the needle. This will result in an increase in the fluid speed. Finally since the flow rate is directly proportional to the speed of the fluid, the flow rate will increase.