# HEMODYNAMICS

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### -The Doppler Effect is explained by a change in ____ due to ____ of the ____ or ____ -There is also a change in ____

-frequency, motion, sound source, reflector
-wavelength

### -A reflector moving towards the source leads to an ____ in frequency -A reflector moving away from the source leads to a ____ in frequency

-increase (positive shift)
-decrease (negative shift)

### Doppler shift is the difference between?

the frequency going into the body and the frequency returned to the transducer

### Blood Flow: -blood is composed of? (4) -blood is about ___% cells

-plasma, erythrocytes, leukocytes, and platelets
-40 (hematocrit)

-bleed
-clot

### Fluid Characteristics: Density is

Mass per unit volume
--Mass: An object's resistance to acceleration

### Fluid Characteristics: Viscosity is

resistance to flow

### Fluid Characteristics: Inertia is

resistance to acceleration

inertia

### Fluid Characteristics: Pressure is

force per unit area

-static
-flow to occur
-increased
-higher, lower

### Volume Flow Rate is the -measured in -determined by

Volume of blood that passes a given point per unit time
-mL/m (or s)
-pressure difference and resistance to flow (If resistance increases, volume flow rate decreases)

### Volume Flow Rate: -Flow resistance is determined by -the formula is

-Poiselle's Law (or a variant of it)
-FR = 8 X Length X viscosity/ p X r^4

### Volume Flow Rate: -Flow rate is determined by -flow rate depends on what 4 things?

-Poiselle's Law
-pressure difference, vessel length, vessel diameter and fluid viscosity

constant

### Poiselle's Law Equation

Q = π p r^4/8 l n

### Poiseuille's Law: Q = Quantity of blood π = constant (3.14) p = pressure difference r = vessels radius l = vessel length n = blood viscosity

-Quantity of blood
-constant (3.14)
-pressure difference
-vessel length
-blood viscosity

### Flow is regulated by

pressure and vessel size variations

-increase
-increase
-decrease

-increase
-increase
-decrease
-decrease

-Plug
-Laminar
-Parabolic
-Disturbed
-Turbulent

### Laminar flow: Where is blood flow faster and slower?

faster in the center, slower away from center

### Parabolic flow:

perfect laminar flow

### Plug flow: where is blood flow faster and slower?

very slow at the walls, but still faster in the center

### Blood Flow: Shape depends -small and medium vessels produce a ____ shape. -larger vessels produce a ____ or ____ flow shape.

vessel size
-parabolic
-plug or blunted flow- fairly constant flow speed across vessel

### Laminar Blood Flow: -Occurs in a ____ substance -____ substance -non uniform flow velocities fastest in

-fluid
-viscous
-center of vessel

-viscous drag
-friction

### Parabolic Blood Flow: -Steady, laminar flow in a ___ & ___ tube -Does or doesn't occur very often in the body? Because?

-long and straight
-doesn't because vessels are not long enough

### What blood flow is seen commonly in the body?

non parabolic laminar blood flow

### Average blood flow speed=

½ maximum flow speed (at center of vessel)

### Disturbed Flow: -____ streamlines are altered -Occurs at ____ or ____ -Flow is still in the ____ direction -A type of ____ -Is disturbed flow an indicator of pathology?

-parallel
-bifircations or stenosis
-forward
-laminar
-not nessecarily

### Turbulent Flow: -The direction of this flow is -circular flow is called -where would you see turbulant flow?

-in many directions (chaotic and random), but remains forward overall
-eddie currents
-distal to Dx

### Turbulent Flow: -The flow speed at which turbulent flow occurs is determined by the ____ --which is dependent upon ____ and ____ of fluid and ____ of tube

-Reynolds number
-density, viscosity, diameter

bruits

### Reynold's Number: -formula? -A reynold's number above ____ indicates turbulence

-R = average flow speed X tube diameter X density/viscosity
-2000 (Critical reynold's number)

-elastic
-PI

### Pulsatility: -is the ability of a structure to -depends upon -allows for

-expand and contract
-stroke volume, ventricular ejection time, peripheral resistance and vascular compliance
-flow reversal

### The Continuity Rule: -states that volume flow rate remains -the continuity rule = -if vessel lumen is decreased, flow speed at areas of stenosis will ____

-constant throughout a vessel
-average flow speed X cross sectional area of the vessel
-increase

### The Continuity Rule: -Expressed with a variant of Poiselle's Law: -Doppler shift is directly related to

-Average flow speed = Pressure difference X diameter2/ 32 X Length X viscosity
-flow speed

### Poiselle's Law vs. The Continuity Equation: -Poiselle's Law: deals only with ____ -which means no ____ -as diameter decreases, flow speed ____

-long straight vessels
-stenosis
-decreases

### Poiselle's Law vs. The Continuity Equation: -Continuity Rule: describes a -as diameter decreases, flow speed ____

-short (stenotic) region of a vessel
-increases

### Bernoulli's Equation: -All KE, PE and work are ____ -Energy is lost through ____

-conserved
-friction (changed to heat (inertial loss))
***p + rgh + 1/2 rv2 = B

### Bernoulli's Equation: -Pressure at a region of stenosis is less than -As flow energy increases, pressure energy ____ -A drop in pressure associated with high flow speeds at a ____

-proximal or distal to that region
-decreases
-stenosis

### Bernoulli's Equation: -formula

-P1 - P2 = 4 V2
--Pressure Drop = ½ X density X (flow speed )^2

### Arterial vs. Venous Flow: Pulsatility vs. Respiratory Changes -Arteries have a higher or lower pressure than veins? -wall composition

-higher
-Internal Elastic Lamina, External Elastic Lamina

### Hemodynamics: -Intravascular Pressure -Cardiac Output

-heart contraction
static filling
hydrostatic pressure
-volume per minute

### Venous Flow: -are veins more muscular or elastic? -As resistance in peripheral arteries increased venous return ____ -Vary with ____ and show ____ changes -larger veins will have ____

-muscular
-decreases
-pressure, respiratory
-valves

### Flow Variations: -Normal flow is considered -As lumen size increases you can what kind of flow? -Also as lumen size increases, you can get varied flow patterns (3)

-laminar
-plug flow (more uniform velocities)
-eddy flow
high velocity flow
stagnant flow

### Flow Variations: -As vessels turn the velocities will be higher where?

at the outer edges of the vessel

-capillary bed
-Ps - Ed/ Ps
-0.7, 0.7

### Resistance: -the less capillaries available, the ____ resistance and the ____ the RI -high resistance signals lack ____ flow or have ____ diastolic flow

-more, higher
-diastolic, reverse

baseline

### Flow Variations: -As vessels near critical stenosis you may see ____ ____ --filling in of the ____ ____ --velocities are increased or decreased?

--systolic window
-increased

### Flow Variations: As vessels stenoes -effects vary with degree of ____ and normal vessel ____ -effects do not affect hemodynamics until about ___% stenosis -If a vessel started as low resistance generally the vessel loses ____ flow as pathology worsens

-stenosis, characteristics
-60
-diastolic

phasicity

### Pulsatility: -applies to ____ only -describes the amount of ____ of walls -PI=

-arteries
-elasticity
-Ps - Ed / mean velocity

-FREQUENCY
-parallel

-F r - F i
-KHz, MHz

audible sound

-2 FoV cos θ / C
-77 Fd/Fo cos θ

-increase
-decrease
-decrease

-down
-0
-1
-increase

-increase

-30-60
-0
-90

-lower
-25

Example: