CVT 100 #7 Physics PP Flow Behavior Flashcards
Laminar blood flow:
moving in concentric layersLaminar flow is orderly,undisturbed flow.

Two configurations of laminar flow:
- Parabolic profile 2. Plug or blunt profile

Spectral Doppler from internal carotid artery:
Systolic upstroke has very narrow range of velocities (plug) Diastolic component has wider range of velocities (parabolic)

Parabolic flow profile: Velocity highest in center…
Velocity highest in center,dropping off toward walls
Parabolic flow profile: Peak velocity is twice…
Peak velocity is twice the mean velocity
Parabolic flow profile: Velocity at walls is…
Velocity at walls is (theoretically) zero
Plug flow profile: Velocities are the same…
Velocities are the same almost all the way across the lumen (Wall drag still slows down the outer layers)
Parabolic flow profile:
All the time in steady flow Throughout cardiac cycle in small arteries (< 3 mm) During diastole in larger arteries
Plug flow profile:
Systole in larger arteries (> 3 mm) Also, entrances to branches, entrance to stenosis

Disorderly flow:Turbulence
Breakdown of laminar, orderly character of flow Many velocities, many directions Chaotic flow character
Turbulence in the heartcauses
a murmur
Turbulence in the vascular systemcauses
a bruit (broo-ee) (French word for “noise”)
A cardiac murmur during systole is…
Systolic cardiac murmurcan be normal. (“functional murmur”)
A cardiac murmur during diastole is…
Diastolic murmuris never normal.
Factors that increase the likelihood of turbulence:
the Reynolds number Dimensionless number predicting likely onset of turbulence
“Flow disturbance”suggests some degree of
interaction of the laminae (layers)in laminar flow

Turbulence is the extremeof flow disturbance:
many velocities, many directions.
Loss of laminar flow due to metal pin at top, creating “vortex streets”—… The degree of disturbance depends on several factors in the Reynolds equation, Coming soon.
the semi-orderly disturbance downstream.

Basilar artery joins the… then bifurcates into… There is little mixing of the flow from right and left vertebrals within the basilar artery.
Basilar artery joins the two vertebral arteries, then bifurcates into right and left posterior cerebral arteries. There is little mixing of the flow from right and left vertebrals within the basilar artery.

There is little mixing of the flow from____________ within the basilar artery.
right and left vertebrals
The Reynolds equation: V= p= d= n=
Re = Vpd ——- n V = velocity p = density d = diameter n = viscosity
If velocity,density, or diameteris increased,
the likelihood of turbulence is increased.
Bigger diameter—>
—>more room for un-laminar flow to get started(walls help to stabilize flow)



