Physiology And Hemodynamics Flashcards by kristen Leboeuf

How much blood does the heart pump into the aorta when it makes a blood pressure pulse

70 milliliters

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How does the aortic valve know to open in order to pump blood

When the left ventricle pressure exceeds the pressure in the aorta

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______ heart rate delivers an ______ blood pressure.

Increase or decrease

INCREASED heart rate delivers an INCREASED blood pressure

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Put the following in order from blood circulation out and back into the heart
*aorta *arterioles * venules. *Vena Cava. *left ventricle. *large arteries. *capillaries. *large veins. *right atrium

Left ventricle -> aorta -> large arteries -> arterioles -> Capillaries -> Venules -> large veins -> Vena cava -> right atrium

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How does the heart help maintain a high pressure gradient between arteries and veins

The pumping action of the heart results in a high volume of blood into arteries

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What determines the AMOUNT of blood entering the arterial system

Cardiac output

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What determines the amount of blood leaving the arterial system

Arterial pressure and total peripheral resistance

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Pressure is greatest at the ____, and decreases as it moves.

Greatest at the heart.

*the pressure difference helps maintain blood flow

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Movement of any fluid medium between two points requires two things…. What are they

A pathway for fluid to flow
Pressure difference (high pressure to low pressure)

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The amount of flow depends on…

Energy difference (including losses resulting from fluid movement)
Resistance that tends to oppose movement

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What kind of resistance causes high flow rate

Low resistance

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What kind of resistance causes lower flow rate

Higher resistance

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The total energy contained in moving fluid is the sum of? (3)

Pressure
Kinetic energy
Gravitational energy

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Potential/stored energy is which kind

Pressure energy

released when walls recoil
expressed in mmHg

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Velocity is which form of energy

Kinetic energy

small part of circulation
expressed in fluid density and velocity (cm/s)

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This type of energy is the weight of the column of blood extending from the heart to the level where pressure is measured

Gravitational energy (hydrostatic pressure…HP)

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If there is a 0mmHg (HP) against arteries and veins at the ankle the patient is in what position

Supine (if patient is average size)

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If an average sized supine patient decides to stand, what happens to the HP

Adds about 100mmHg to ankle vessels

Ankle pressure = circulation pressure plus 100mmHg

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The tendency of fluid to resist changes in its velocity

Inertia

body at rest tends to stay at rest

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As blood moves farther out to the periphery, energy dissipated largely in the form of _______

Heat

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in the equation for resistance, R(resistance) is directly proportional to which two factors

Viscosity and length
*variables in the numerator of the equation

R= 8nL/(pie)r^4

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In the equation for resistance, R(resistance) is inversely related to which variable?

Radius
*variable in denominator

R= 8nL/(pie)r^4

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Of the three variables in the resistance equation, which one effects resistance the MOST
Viscosity, length, or radius

Radius

*a change in the radius means there was a change in the vessel diameter

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The internal friction of a fluid is measured by?

Viscosity

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What effect does elevated hematocrit have on the blood viscosity?

Will increase the blood viscosity bc it effects the THICKNESS of the fluid

What effect will anemia have on blood viscosity?

Decreases blood viscosity

____ viscosity = _____ velocity

``` Increased viscosity(friction) = DECREASED velocity While.... Decreased viscosity = INCREASED velocity ```

what term described flow that is evenly distributed during systole

Laminar

What kind of flow is considered "stable flow"

Laminar

______ flow is normally seen at vessel origin and/or initial cardiac upstroke

Plug flow

______ flow is usually seen downstream once the laminar flow is fully developed

Parabolic flow

Inertial energy loss occurs when this happens | 2

Directional change and/or velocity change

What type of energy loss occurs at the end of a stenosis? Viscous energy loss Internal energy loss

Inertial energy loss

Poiseuilles equation helps define how much fluid volume moves through the vessel with these three variables

Pressure(P), volume flow(Q), resistance(R) Q = P/R

Radius of a vessel is ______ proportional to volume flow

Directly

The law of conservation of mass explains the relationship between these two things

Velocity and area (inversely related) Q = A x V

Benoullis law uses the relationship between what two variables

Pressure and velocity (inversely related)

Total energy contained in moving fluid is the sum of what?

the sum of pressure, kinetic and gravitational energy

What's another name for pressure gradients

Flow separation

What can cause flow separation (pressure gradient) to occur? (3)

Regions with... Reverse flow, stagnant flow, or little movement EXAMPLES: valve cusp site, anastomosis of bypass graft

Reynolds Number(Re) helps to predict when fluid becomes unstable/disturbed by using these two variables

Pressure and flow relationship

With Reynolds Number (Re), laminar flow is considered disturbed when it is GREATER than this number

Greater than 2000 | *unitless number

STEADY flow originates from a ____ _____ ____

Steady driving PRESSURE

This flow changes both driving pressure conditions as well as the response of the system (Steady VS pulsatile)

Pulsatile flow

Describe what happens during systole

Aortic valve opens causing foward flow throughout the periphery (fluid acceleration)(initial release)

Describe what happens during late systole/early diastole

Temporary flow reversal due to a phase shift of negative pressure gradient and peripheral resistance ** think of the "biphasic" portion of a waveform

The dicrotic notch is related to the closing of ____ and the influence of _____ ______

Closing of aortic valve and influence of peripheral resistance * when aortic valve closes diastole begins *

Describe late diastole

Flow is foward again

T/F | Diastole reflects where the blood is going to

TRUE

The ICA, vertebral, renal, celiac, splenic, and hepatic arteries are all examples of what resistance

LOW resistance * organs you can't live without *

The ECA, subclavian, aorta, iliac, fasting SMA, and arteries in extremities are all what type of resistance

High resistance

The reversal component in a high resistance waveform may disappear distal to ______ b/c of a decreased peripheral resistance

Stenosis | *this is secondary to ischemia

What is the appearance of a waveform that is distal to a significant stenosis

Can show... low resistance More rounded Weaker strength

What kind of flow should we expect proximal to a significant stenosis

May become... monophasic Higher resistance

VasoCONSTRICTION causes medium/small arteries to have a ______ in pulsitility, and a ______ in minute arteries

``` Medium/small = increase Minute = decrease ```

VasoDILATATION causes medium/small arteries to have a ______ in pulsitility, and a ______ in minute arteries

``` Medium/small = decrease (lower resistance) Minute = increase ```

At rest, can blood flow seem normal even if there is a stenosis or complete occlusion of a main artery, why?

Yes, because of collateral networks

With arterial obstruction, the collateral channels may have an altered flow. What are the changes that occur in the collateral channel flow

Elevated velocity Increased flow volume Pulsatility changes

What are some causes of exercise

Peripheral vasodilation which lowers distal peripheral resistance, enhancing blood flow

Exercise helps regulate this due to the vasoconstriction and vasodilatation of the vessels in the skeletal muscles

Regulates body temperature bc of the sympathetic nervous system response

_____ is a key vasodilator of the resistance vessels in the skeletal system

Exercise

The ability of most vascular beds to maintain constant level of blood flow over a wide range of perfusion pressures is?

autoregulation

In resistant vessels, constriction causes BP to ___, and dilation causes BP to _____

``` Constriction = rise Dilatation = fall ```

A vigorous exercise causes vasodilatation, making the waveform look...

Low resistant with monophasic flow

Vasoconstriction and pulsatile waveform is seen with a warm or a cold extremity?

Cold * warm extremity means vasodilatation and a continuous waveform

T/F | distal effects of obstructive disease may only be detectable following stress (exercise)

True

A hemodynamically significant stenosis causes a notable reduction in what two things

Volume flow and pressure

A cross sectional area reduction of 75% = a diameter reduction of what percent

50%

Effects of flow abnormality produced by a stenosis depends on factors such as...

Length/diameter/shape of narrowing Multiple obstructions in the Same vessel Obstructions in different vessels that are parallel Pressure gradient

A dampened waveform is usually _____ to a stenosis

Proximal

Entrance into a stenosis produces an increased Doppler shift frequencies (DSF), which makes the waveform look like what

``` Spectral broadening ( wide range of velocities) Elevated velocities ```

Flow disturbance occurs with what kind of velocities

High velocities and eddy currents

Post-stenosis causes what kind of flow

Turbulence | (Flow reversal, flow separation, vortices/eddy currents

Physiology And Hemodynamics Flashcards

(73 cards)