Flashcards in Arterial Physiology and Hemodynamics Deck (40)
Cardiac contraction begins:
Pressure in the left ventricle rises rapidly.
Left ventricle pressure exceeds that in the aorta.
aortic valve opens, blood is ejected, BP rises
The heart pump:
Generates the pressure to move the blood.
Results in a pressure wave that travels rapidly throughout the system, demonstrating a gradual transformation as it travels distally.
Each beat pumps about how many milliliters of blood into the aorta causing a blood pressure pulse?
What governs the amount of blood that enters the arterial system?
What determines the amount of blood that leaves the arterial system?
arterial pressure and total peripheral resistance
movement of any fluid medium between two points requires what two things?
A pathway along which the fluid can flow.
Difference in energy levels (pressure difference)
The amount of flow depends upon what?
Any resistance which tends to oppose such movement.
Flow depends upon resistance and flow rate:
higher flow rate
lower flow rate
Total energy contained in moving fluid is the sum of what energies?
pressure, kinetic, and gravitational
What is the major form of energy for circulating blood?
pressure energy (mmHg)
What energy is small for circulating blood? Expressed in terms of fluid density and its velocity measurements.
What is equivalent to the weight of the column of blood extending from the heart to level where pressure is measured?
gravitational energy or hydrostatic pressure
When supine there is 0 mmHg against the arterires and veins at the ankle. When standing the HP increases to what?
An energy gradient is needed for what?
moving blood from one point to another. greater the gradient, the greater the flow.
L= vessel length
R is directly proportional to variables in numerator and indirectly to the variable in the denominator.
What has a more dramatic effect on resistance than viscosity and vessel length?
factors affecting resistance to flow?
physical properties of the fluid and what its moving through
viscosity ans velocity
viscous energy loss is due to what?
increased friction between molecules and layers
Inertial losses occur with deviations from laminar flow due to what?
Changes in direction and/or velocity. occurs at the exit of a stenosis
Poiseuilles equation helps answer the question of how much fluid moves through vessel and defines the relationship between what?
Pressure, volume flow, and resistance
area and velocity
sum of pressure, kinetic, and gravitational energies. If one changes the others make up for the difference in order to maintain the original total fluid energy.
velocity and pressure
Late systole/early diastole:
Temporary flow reversal
Forward flow again
low resistance flow consists with what? continuous
ICA, vertebral, renal, celiac, splenic, hepatic
high resistance flow occurs in what? pulsatile
ECA, subclavian, aorta, iliac, extremity arteries, fasting SMA
Doppler flow distal to a significant stenosis is?
lower resistance, more rounded, and weaker in strength
Doppler flow prox to stenosis is what?
A normally high resistant signal may become monophasic closer to stenosis.