Get ahead with a $300 test prep scholarship
| Enter to win by Tuesday 9/24
Chapter 2: Physiology and Hemodynamics of Arterial System
Terms in this set (84)
Each beat pumps about how much blood into AO
70 mL each beat
What occurs in the LT ventricle during contraction
Pressure in LT rises rapidly
LT vent pressure exceeds that in the AO
What happens to the AO valve during contraction
AO valve opens and blood is ejected (BP rises)
Increased heart rate delivers and increased blood ___________________
when the heart pumps, it results in a high volume of blood in the arteries to maintain a __________ pressure gradient between arteries and veins
What determines the amount of blood that leaves the heart?
arterial pressure and total peripheral resistance
Where is the pressure the greatest?
at the heart and decreases as the blood travels away
In order for movement to occur, what is required?
-pathway for fluid to flow
-Difference in energy levels (pressure difference)
What does the amount of flow depend on?
higher flow rate
lower flow rate
What is the total energy contained in a moving fluid the sum of?
Potential (Pressure), Kinetic, and gravitational energy
Stored energy and is the major form of energy for circulation of blood
Where is potential energy stored?
in the vessel wall
What are the units for potential energy
What type of energy is small for circulating blood?
How is kinetic energy expressed?
Fluid density and velocity measurements
What type of energy is "movement"
Gravitational energy aka
Hydrostatic pressure (HP)
What is gravitational energy equivalent to?
the weight of the column of blood extending from the heart to the level where pressure is measured
When supine, what is venous pressure?
Why is the venous pressure (gravitational/HP) 0mmHg when in supine position?
because arteries and veins are at the same level as the heart
When in supine, there is 0mmHg against the arteries and veins at which part of the body?
ankle (Ankle P= Circulatory P + 0mmHg)
When standing, does hydrostatic pressure increase or decrease?
When standing, there is how much pressure against the arteries and veins at the ankle?
100 mmHg (Ankle P= Circulatory P + 100mmHg)
What relates to the tendency of a fluid to resist changes in its velocity
As blood moves out toward the periphery of the vessel what happens?
energy is dissipated in the form of heat
R= 8 x viscosity x length / pi x radius ^4
What does severe anemia do to blood viscosity?
What does inertial loss come from?
changes in direction or velocity
What does Poiseuille's equation define the relationship between?
pressure, volume flow, and resistance
What does Poiseuille's equation help determine
how much fluid flow through a vessel
Q= (p1-p2) x PI x r^4 / 8 x L x Viscosity
When a pt is supine, is there a change in hydrostatic pressure?
If area increases, what happens to velocity?
The total energy in moving fluid is the sum of what?
pressure, kinetic, and gravitational energies
What deals with the relationship between pressure and velocity?
If velocity increases, what happens to pressure?
If velocity decreases, what happens to pressure?
in a stenosis, what does velocity and pressure do?
velocity increases and pressure decreases
After a stenosis, what does velocity and pressure do?
Velocity decreases and pressure increases
When is comes to Bernoulli's law, how are velocity and pressure related?
Why do pressure gradients (flow separations) occur? Give examples
due to geometry changes without disease
example: Bifurcation or tortuous vessel
what do flow separations result in? Give examples.
regions with stagnant or little movement
Examples: bypass graft anast. site, valve cusp site
forward flow throughout the periphery
temporary flow reversal
late systole/early diastole
flow is forward again following the temporary flow reversal
continuous/steady flow that feeds a dilated vascular bed
Examples of low resistance arteries
pulsatile flow with flow reversal
Examples of high resistance arteries
The reversal component in high resistance flow may disappear following a stenosis due to what?
decreased peripheral resistance secondary to ischemia
How does the waveform appear distal to a stenosis?
more low resistance with a rounded waveform
How is flow proximal to a stenosis?
higher resistance with minimal diastole
pulsatility in small/medium arteries increases with what?
pulsatility in minute arteries decreases with what?
pulsatility in small/medium arteries decreases with what?
pulsatility in minute arteries increases with what?
As the inflow pressure falls as a result of stenosis, what is the natural response of the periphery vessels? Vasodilate or vasoconstrict?
in the presence of a stenosis or occlusion, how would total blood flow still be normal?
-Decrease in peripheral resistance
Arterial obstruction may alter flow in collateral channels nearby or further away from site of obstruction. Changes include:
-increased volume flow
-reversed flow direction
-waveform pulsatility changes
how does exercise affect blood vessels/blood flow?
-Decreased distal peripheral resistance
-Increased blood flow
Vasoconstricion and vasodilation of blood vessels within the skeletal muscles also influenced by sympathetic innervation fibers function primarily for what?
regulation of body temperature
what is the best single vasodilator of resistance vessels within skeletal muscles?
ability of most vascular beds to maintain constant level of blood flow over a wide range of perfusion pressures
how does the constriction of blood vessels affect blood pressure?
how does the dilation of blood vessels affect blood pressure?
How is the blood flow pattern in extremity arteries after vigorous exercise.?
exercise causes reduced flow resistance (vasodilation) which results in low resistance monophasic flow
How is the blood flow pattern with proximal arterial obstruction?
monophasic due to peripheral dilation
when may high resistance flow be seen in arteries?
-distal arterial obstruction
How will the flow be in a COOL extremity?
pulsatile flow due to vasoconstriction
How will the flow be in a WARM extremity?
Continuous steady flow due to vasodilation
Waveforms may not be altered when pathology is present due to what?
Distal effects of obstructive disease may only be detectable following what? Give examples.
stress ( exercise or hyperemic evaluation)
-Even distribution of frequencies at systole
-Lower flow at walls
-Faster flow in center
a significant stenosis causes a notable reduction in what?
volume flow and pressure
cross sectional area reduction of 75%= diameter reduction of how much?
Abnormal flow produced by a stenosis depends on what?
-Length, diameter, shape, degree of narrowing
-Obstruction in different vessels that are parallel
How would the resistance be with multiple obstructions in the same vessel?
higher because resistance to flow is additive
How would the resistance be when there are obstructions present in different vessels that are parallel?
lower because only part of the blood in going through each narrowing
How is flow usually proximal to a stenosis
dampened with or without disturbance
how is flow within a stenosis?
How is flow distal to a stenosis?
Distal to a stenosis, how is energy expended?
energy is expended as heat as eddy currents /vortices work against blood viscosity