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5
how many liters of blood does the circulatory system contain?
solids, liquids, gases
what 3 categories is matter generally classified into?
fluids*
materials that flow and conform to the shape of their containers
to flow
to move in a stream, continually changing position and possibly direction
the right
what side of the heart is related to the venous system?
the left
what side of the heart is related to the arterial system?
viscosity
the resistance to flow offered by a fluid in motion
ɳ (poise)= kg/m-s
what are the units of viscosity?
viscosity
what is the property of a fluid that resists the force which tends to cause it to flow?
low
is water's viscosity high or low?
high
is honey's viscosity high or low?
50%
viscosity of the blood plasma is about ___% greater than that of water.
5 times
the viscosity of normal blood is about ___(#) times that of water
pressure=force/area
the driving force behind fluid flow
dyne/cm^2
what are the units for pressure?
difference
a pressure _____ is required for flow to occur
direct
what is the relationship between pressure and flow rate?
no
equal pressures = _____ flow
volumetric flow rate
the volume of blood passing a point per unit of time
Q, milliliters/second, mL/s
what is the unit for volumetric flow rate?
Q (mL/s) = ΔP (dyne/cm^2) / resistance to flow (poise)
what is the equation for volumetric flow rate?
R (poise) = ΔP (dyne/cm^2) / Q (mL/s)
what is the equation for viscosity?
the pressure difference (or gradient) and the resistance to flow (viscosity)
what is the volumetric flow rate in a long straight tube determined by?
direct
what is the relationship between pressure and volumetric flow rate?
inverse
what is the relationship between viscosity and volumetric flow rate?
Q=[ΔP π x d^4] / [128 L * ɳ]
What is Poiseuille's equation? *for steady flow in long, straight tubes
R (g/cm^4 -s) = 8 x L (cm) x ɳ (poise) / pi * [r^4 (cm^4)]
flow resistance equation
decrease it by 1/16 its original value
what does doubling the radius of a tube do to its resistance?
increases its resistance by 16 times its original value
what does decreasing the radius of a tube by half do to its resistance?
direct
what's the relationship between tube diameter and flow rate?
inverse
what's the relationship between tube length and flow rate?
low
does the aorta have low or high resistance?
high
do the arterioles have low or high resistance?
50%
how much of the total resistance in the systemic circulation do the arterioles account for?
flow
to move in a stream continually changing position and possibly direction
fluids
a material that flow and conforms to the shape of its container
flow resistance
pressure difference divided by volume flow rate for steady flow
volumetric flow rate
volume of fluid passing a point per unit of time
pressure gradient (slope)
pressure difference divided by distance between the two pressure locations
viscosity
resistance of fluid to flow
pulsatile, phasic, and steady
what are the 3 basic forms of blood flow?
pulsatile blood flow
occurs when blood moves with variable velocity. Blood accelerates and decelerates as a result of cardiac contraction. Seen in arterial circulation.
phasic blood flow
occurs when blood moves with variable velocity. blood accelerates and decelerates as a result of respiration. seen in venous circulation.
steady blood flow
occurs when blood moves at a constant speed or velocity. present in venous circulation when individuals stop breathing for a brief moment
plug, laminar, parabolic, disturbed, turbulent
what are the 5 categories flow can be divided into?
plug flow
flow with all fluid portions traveling with the same flow speed and direction
entrance to a vessel
where does plug flow occur?
unit
plug flow is similar to the motion of a solid object that does not flow but moves as a _____
laminar flow
flow in which fluid layers slide over each other in a smooth, orderly manner, with no mixing between layers
layer
'lamina' = _____ = silent flow
straight and parallel to each other
what describes the streamlines in laminar flow?
center of the tube
where is flow speed at its max in laminar flow?
at tubes walls
where is flow speed at its min in laminar flow?
decreasing
a _____ profile of flow speeds from the center to the wall is present in laminar flow
parabolic flow
a form of laminar flow with a profile in the shape of a parabola
1/2
in parabolic flow, the average flow speed across the vessel is equal to ___(#) the max flow speed
disturbed flow
a form of laminar flow that cannot be describes by straight parallel streamlines
forward
in disturbed flow, particles of fluid flow in the _____ direction
stenosis or at bifurcation
when does disturbed flow occur?
turbulent flow
random, chaotic, swirling, hurricane-like with rotational patterns, multidirectional flow of a fluid with mixing between layers
no
is turbulent flow laminar?
Bruit or murmur
the unusual sound that blood makes when it rushes past an obstruction or stenosis
cardiovascular pathology and elevated blood velocities
what is bruit or murmurs associated with?
transition from high flow speed in narrow channel to slow flow in a broad stream
where does turbulent flow occur?
false! forward net flow is still maintained
T or F
With turbulent flow, net flow can be forward or backward or mixed.
mmmmmmm
what does MPV pulse wave look like when the patient is breathing normal?
iiiiiiiiiiiiiiiiii
what does MPV pulse wave look like when the patient is holding their breath?
1. laminar flow
2. entrance effect: 'plug flow'
3. laminar flow
4. 'steeper' parabolic laminar
5. entrance effect: 'plug flow'
6. exit effect: turbulence
7. laminar flow
what are the 7 steps of flow through a rigid tube?
pulsatile flow (arterial)
non-steady flow that accelerates and decelerates with each cardiac cycle
true
T or F
With pulsatile flow, in distensible vessels, includes added forward flow and/or flow reversal over the cardiac cycle in some locations in the circulation
Windkessel effect
later in the cycle, when the driving pressure is reduced, the compliant vessel is able to contract, producing extended flow later in the pressure cycle
continuity rule
blood is neither created nor destroyed as it flows through a vessel
stenosis
flow speed increases at a _____ and turbulence can occur distal to it
true
T or F
Volumetric flow rate must be constant proximal, within and distal to a stenosis
Poiseuille's law says flow speed decreases with smaller diameters, while continuity rule states flow speed increases with smaller diameters
Why do Poiseuille's law and the continuity rule seem contradictory?
Poiseuille's law-long, straight vessel with no stenosis, refers to entire vessel
continuity rule-refers to diameter of a shorter portion of a vessel (stenosis)
what is the important difference between Poiseuille's law and continuity that accounts for the contradiction?
Bernoulli's equation
assuming there is no energy lost to heat, in a closed system, the energy at point 1 must equal the energy at point 2.
Bernoulli effect
pressure reduction in a region of high-flow speed
inverse
in the Bernoulli effect, what is the relationship between flow speed and pressure?
increase
In the Bernoulli effect, to maintain flow continuity, flow speed must (increase/decrease) through a stenosis
drop
with the Bernoulli effect, does the pressure drop or rise in a stenosis?
Δ P = 4 (flow speed at stenosis)^2
what is the pressure drop formula? (dont need to know)
-change in flow direction
-increased velocity as vessel narrows
-turbulence downstream from stenosis
-pressure gradient across the stenosis
-loss of pulsatility
What are the effects of a stenosis?
Ohms' Law
current = Δ voltage / resistance
the numerator for flow is Δpressure but the numerator for ohms' law is Δvoltage BUT the denominator is resistance for both
what are the similarities and differences between flow and ohms' law?
Doppler effect
A change in frequency caused by motion of a source or reflector
