18 Hemodynamics Practice Flashcards
What is the equation that describes the relationship between pressure gradient, resistance, and flow in a vessel?
Pressure gradient= flow x resistance
(Flow and pressure gradient have a direct relationship. One goes up, the other goes up.
Resistance and pressure gradient have an inverse relationship. )
This is a Variation on OHM’s law (whiche typically applies to electrical systems)
What is ohms law
A law in electrics where voltage= current•resistance
Voltage and current have a direct relationship.
Voltage and resistance have an inverse relationship.
Blunt flow is the other term for plug flow-
true or false
True
The flow of blood is dependent on two factors…
Resistance
Pressure gradient along a vessel
Resistance to bloodflow is dependent on three factors…
The viscosity of the blood
Radius of the lumen
length of the vessel
The maximum velocity is right after the stenotic area.
True or false?
False the maximum velocity is achieved at the most severe narrowing of a stenosis
Kinetic energy, (which is the energy associated with moving objects and determined by its mass and speed) is the maximum at the stenotic area. True or false?
True it is at max velocity- therefor the Kinetic energy is also at the maximum
Pulsatile flow is seen in _____and it’s the result of______.
Arteries
Cardiac contraction
(blood has various velocities during the cycle)
_____ flow is seen in _____and it’s the result of______.
Phasic
Veins
Respiration
PSV stands for
Peak systolic volume
EDV stands for
End diastolic volume
As more vessels dilate in the peripheral circulation, resistance is _____and cardiac output becomes______
Decreased
Greater
For a parabolic velocity profile, the average velocity through the lumen is equal to half the maximum velocity. True or false
True because it is bullet shaped.
The X axis on a spectral graph represents
Time
The Y axis on a spectral graph represents
Velocity
What’s the term that used to describe the relationship between velocity and pressure in the blood vessels?
Velocity profile
Plug flow is seen at the entry of arteries true or false
False plug flow is mainly only large vessels like the thoracic Aorta.
Velocity decreases in the area post stenosis true or false
True
The total energy at a specific location within the circulation is the sum of_____,_____,and ______energies.
Kinetic energy
Pressure energy
Gravitational energy
In plug flow, all layers of blood have the same velocity. True or false
True
Laminar flow is seen in long, straight arteries. True or false?
True
Disturbed flow is only seen in pathological conditions of the vessels. True or false
False disturbed flow is seen in curbing, branching, diverging vessels and by projections into the lumen.
The term that is used to describe turbulent flow currents are _____and______.
Eddie currents
A vortex
Turbulent flow is seen right after the stenotic area. True or false?
False. flow reversal is seen immediately after stenosis followed THEN by turbulent flow
The sound is called ____or ______which can be heard by the stethoscope at the site of stenosis
Murmur
Bruit
The pressure energy is the maximum right after the stenotic area true or false?
True. Kinetic Energy drops after the stenotic area and pressure energy goes up.
According to the law of conservation of energy, the sum of _____energy and _______stays the same.
Kinetic energy
Pressure energy
blood energy loss is due to three factors…
Viscous energy loss
Frictional energy loss
Inertia energy loss
When the Kinetic energy increases at an area in the vessel, the pressure energy increases as well, true or false?
False according to the law of the conservation of energy- as Kinetic energy increases, pressure energy decreases.
If the Reynolds number is less than 1500, this reflects laminar flow. True or false
True laminar flow is represented by a number less than 1500. Turbulent flow is a Reynolds number of greater than 2000
An area of reversal of flow is seen right after the stenotic area and before the turbulent flow is seen true or false
True
What are the units that are used to measure:
A:blood flow
B:velocity
C:blood pressure
Flow- ml/s
Velocity-cm/s
Blood pressure- mm/hg
Intravascular pressure is produced by three different pressures…
Which is the least important?
Pressure from heart contraction
Static filling pressure
Hydrostatic pressure.
Static filling pressure
Blood flow in the vessels because of its energy gradient not because of its pressure gradient, true or false?
True. Blood flow is the result of its energy gradient.
What does inertia mean?
An objects’ tendency to resist changes in velocity
The tissue vibration at the point of stenosis is called a
Thrill
The primary regulatory control on cardiac output is
Peripheral resistance
In polycythemia, resistance to bloodflow is increased true or false
True- due to increased blood cells and increased blood viscosity anemia with its decreased blood cells resistance is decreased
For a similar increase in pressure, a vein can contain 6 to 10 times the volume of blood as an artery of a comparable size true or false
True
What is the equation that describes the relationship between the true pressure hydrostatic pressure and measured pressure of the blood?
Measured pressure =
True pressure + hydrostatic pressure
In a supine patient, the hydrostatic pressure at the knee is 30 mm/HG true or false
False supine patient have a hydrostatic pressure of zero everywhere
In a standing patient, the hydrostatic pressure at the heart level is 0MM/HG true or false
True the heart is the reference point
Flow and resistance are directly related true or false?
False flow and resistance have an inverse relationship
What is the true pressure at the knee level on someone who is standing and they are measured pressure was 210 MM/HG?
135 MM/HG is the true pressure. Knee is +75
Bernoulli’s principle describes the relationship between _____and_____
Velocity
Pressure in blood vessels
What is the hydrostatic pressure at the hip level on a supine patient if the true pressure is 15 MM/HG?
The hydrostatic pressure at the hip level on a supine patient is zero…because they are supine
When the diameter of a vessel increases, the flow decreases true or false
False flow increases when resistance decreases like when a diameter on a vessel widens
Exercise causes _____of lower extremity arteries which_____ the resistance to flow.
Dilation
Decreases
When the viscosity of blood decreases the resistance increases. true or false?
False when the viscosity decreases, resistance decreases
During inspiration, the diaphragm ascends increasing pressure in the thoracic cavity true or false?
False the diaphragm descends during inspiration
______ flow is the localized slow rotation of concentric blood layers
Eddie
Flow and pressure gradient are directly related true or false?
True
During expiration Venus flow in the lower extremities is increased true or false
True.
During inspiration, Venus flow in the upper extremities is increased true or false
True
What is the measured blood pressure at the ankle on a standing patient with true pressure which is 130 MM/HG
The measured pressure is 230 MM/HG
The ankle is +100
Eddie flow occurs at arterial by furcation, within vessels undergoing rapid expansion of luminal diameter, and distal to an obstruction. True or false
True
Bernoulli’s principle is derived from…
The law of conservation of energy which states that energy is never lost- it simply changes form
The change in velocity within the heart cycle are characterized by the _____index.
Pulsatility index
What is the mathematical relationship for the pulsatility index?
PI=PSV-EDV/mean volume
Blood loses its energy only when it accelerates true or false?
False energy is lost both with acceleration and deceleration
Turbulent flow converts flow energy into other forms such as _____and______.
Sound
Vibration
_______ Number indicate whether the flow is laminar or turbulent
The Reynolds number
What is the Reynolds equation?
Renolds #=p•d•v/n
P is density of fluid
D is diameter of vessel
V is velocity of the blood
N is viscosity of the fluid
A zone of stagnant flow, called________,divides the circular notion of Eddie flow from the central region of high velocity flow
Flow separation
________ slow is the term used to describe laminar flow
Parabolic
Where do we see phasic flow?
Phasic flow is found in veins
Where do we see pulsatile flow?
Pulsatile flow is found in arteries
Velocity changes in the visceral arteries between ______and_____.
Systole
Diastole
Where do we see steady flow?
Steady flow is seen in veins, upon cessation of breathing.
The velocity profile is highly variable depending on anatomical location, true or false?
True
As pressure gradient decreases, flow increases true or false
False pressure gradient and flow have a direct relationship as one increases the other increases
