Lecture 20 Flashcards
(34 cards)
Plug flow is at ________ to tubes
Enterance
Plug flow blood moves as
A unit
In Plug flow there is the same ______ across the vessel
Speed
Two types of flow
Laminar
Turbulent (non-laminar)
3 types of laminar flow
Plug flow
Parabolic
Disturbed flow
Parabolic/ laminar happens when
After entering the straight tube
The fastest speed in parabolic is where
The center of the tube
During doppler we assess where in the tube
The centre
The slowest speed in parabolic is where
Tube wall
Average flow speed in parabolic is
Half the fastest speed
Disturbed flow occurs at a
Stenosis or bifurcation
Disturbed flow is still _______ flow but streamlines are not ____
Laminar
Straight
Disturbed flow is non- _____
Parabolic
Turbulent flow usually occurs after a
Significant stenosis
Turbulent flow can also be called what 4 things
Chaotic, multidirectional, multispeed flow, non laminar
Turbulent flow is related to
Eddies —> flow in circles but still with forward net flow
With turbulent flow physician may hear a
“Bruit”
Often main reason for the ultrasound
Turbulent flow depends on
Reynolds number
Critical reynolds number =
2000 for blood
Flow must surpass ________ to cause turbulent flow
a critical reynolds #
Reynolds number equation
Re= pvd/n
, p = density of fluid , v = velocity of fluid , d = diameter of pipe , n = viscosity , Re= reynolds number
What is a stenosis
Partial blockage
Occlusion
Complete blockage
In compliant vessels we observe
Added forward flow and reversal of flow
