Arterial Physiology Flashcards
What is known as the flow through two points being directly proportional to the potential difference across two points, and inversely proportional to the resistance between them?
Ohm’s Law
What is known as the measure of a blood vessel’s ability to increase the volume of blood it holds without a large increase in blood pressure?
Capacitance
The total energy of a system is made up of?
Kinetic and potential energy
What is the potential energy in the bodies arterial system?
Intravascular pressure
What is the kinetic energy in the bodies arterial system?
Velocity of moving blood
What is the pressure of the right atria in the heart?
2-6 mmHg
What is the highest and lowest pressure chamber in the heart?
Highest = LV
Lowest =RA
Is gravitational potential energy increased or decreased BELOW the reference point (RA of the heart)?
Decreases below the reference point
What is known as the pressure within vessels related to the reference point? (RA)
Hydrostatic pressure
Does hydrostatic pressure increase or decrease as you go lower in the body?
Increased due to the weight of the column of blood within the vessels
The farther you go from the reference point does what to the hydrostatic pressure?
Increases
What is the most important influence on blood viscosity?
Hematocrit
Inertial energy loss is dependent on what factors?
- Density of blood
- Velocity of flow
T or F? Energy losses because of viscosity effects are greater than those because of inertia?
TRUE
Velocity and flow are related by what equation?
V = Q/A
As diameter decreases, what happens to velocity?
Increases
T or F?The cross-sectional area of the capillaries is greater than that of the Ao?
TRUE - 600x greater
Equation for Ohm’s Law?
R = change in pressure / Q
Equation for Resistance to flow?
R = (8 x viscosity x L) / (pi x r^4)
Changes in vessel resistance are mostly all due to what factor?
Changing radius because it is calculate to the 4th power
Resistance in series?
Sum of all resistances of each vessel
Resistance in parallel?
Reciprocal of the total resistances of the system
What happens to the resistance with more parallel elements in a network?
Resistance will decrease in the system
What do low resistance arterial waveforms look like?
Antegrade forward flow (above the baseline)
What do high resistance arterial waveforms look like?
Both antegrade forward flow (systole) and retrograde flow reversal (diastole)
What is turbulent flow defined by?
Reynolds number (Re)
Re is directly proportional to what factors?
Velocity
Density
Radius
Re is indirectly proportional to what factor?
Viscosity
Turbulence develops mainly due to what changing factors?
Velocity
Radius
What Re number will create turbulence?
> 2000
What is the term used for converting the pulsatile output of the heart to a steady flow through the capillaries via elastic conduits and high-resistance terminals?
Hydraulic filtering
What refers to the ability of a vessel to store energy?
Capacitance
What is the formula for capacitance?
change in V / change in P
How do stiffer vessel walls affect pressure in systole and diastole?
Systole = greater pressure
Diastole = reduced pressure
What happens to vessel capacitance as we age?
Decreases - becomes more stiff
When oxygen levels fall in the arterioles, what happens to the vessel?
Vasodilation to bring more blood flow to the area, increasing oxygen
Fibrous plaque
- smooth surface
- composed of smooth muscle and fibrous tissue
- lacks calcification
Complicated plaque
- Irregular surface
- Loss of the normal endothelium
- Calcification is present
Where does atherosclerosis typically develop?
- Branch points
- Near bifurcations
Where is most inertial energy loss in presence of stenosis?
When blood EXITS a stenosis into turbulent flow
At what point is a stenosis considered ‘critical’?
When the cross-sectional area of a vessel has diminished 75% or greater
What can collateral arteries be separated into?
- Stem arteries
- Midzone collateral
- Re-entry arteries
