Hemodynamics Flashcards by Grace Phillips

circulatory system is

closed

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CO =

5 L/min

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pressure gradient is created by

heart

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RA pressure =

0 mmHg

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flow occurs from ___ to ___ pressure

high to low

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circulatory system is comprised of

heart - arteries- arterioles- capillaries - venules - veins- back to heart

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flow is created by

pressure gradient

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capacitance vessels

veins

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blood makeup

plasma = water, protein

RBC, WBC, platelets

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hematocrit

% of RBC in blood

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flow regulating mechanisms

CO, cardiac function, tone + elasticity of vessels, interconnecting arterioles

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principle point of resistance

interconnecting arterioles

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regulators

interconnecting arterioles

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vasomotor tone

constriction, dilation of vessels

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Starlings law

stretch - > force of contraction of ventricles

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HR is affected by

baroreceptors, chemoreceptors, exercise

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Windkessel effect

elasticity of vessel, wall compliance, tone

reflection of wave back up vessel wall, creates dicrotic notch

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arterial pulse pressure wave

pressure wave is propagated throughout arterial tree with each contraction of heart.
pressure wave velocity increases as it moves into smaller, stiffer peripheral arterioles

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times it takes for pressure wave to travel from heart to foot

250 ms

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arterial pulse pressure wave occurs in

vessel wall, independent of blood

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volume flow

volume of blood passing a point per unit of time

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adult blood flow rate

5 L/min

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Q =

(A) X (TAV)

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Continuity rule

volume in closed system must stay constant. Blood volume is not lost or created (conservation of matter)

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Continuity rule in case of stenosis

since the same volume of blood must pass, but the area is smaller, the velocity therefore must increase

Continuity equation

A1V1 = A2V2

if area is halved, then velocity is

doubled

a change in area affects

pressure and flow

density of blood

1.05 g/mL

viscosity of blood

0.035 poise

viscosity is created by

internal frictional forces within the fluid

viscosity of blood is affected by

hypothermia, polycythemia, severe anemia

Q =

delta P/ R

if resistance increases, Q ____

decreases

if pressure gradient increases, Q ____

increases

Poiseuille's law

describes flow through a tube

Poiseuille's law states that flow is related to

viscosity, radius, length, pressure gradient

greatest factor in Poiseuille's law affecting flow is

radius/diameter

if diameter in stenosis is 1/2 the original lumen, the flow will be reduced ___ times

16 times | r^2

increase in viscosity will ___ resistance

increase

increase in tube length will ___ resistance

increase

increase in diameter will ___ resistance

decrease

decrease in diameter will ___ resistance

increase

2 types of fluid energy

potential, kinetic

E total =

E potential + E kinetic

potential energy is

intravascular pressure and gravitational potential energy

kinetic energy is

related to motion of blood

Bernoulli principle

increase in velocity of fluid occurs simultaneously with a decrease in pressure or potential energy

pressure and velocity are ___ related

inversely

when blood accelerates/decelerates energy is

converted back and forth from potential to kinetic anc back

an increase in velocity will cause a ___ in P

decrease

parabolic flow profile

laminar flow, speed varies across tube, highest in center, slowest at edges,

average velocity in laminar flow

= 1/2 max speed

plug flow

laminar flow, flattened parabola, more uniform in speed

plug flow is usually found in

large vessels, at branch points

jet flow

high velocity at narrowing

disturbed flow

mild turbulence

disturbed flow occurs at

bifurcations, curves, near heart

turbulent flow

non-linear, multiple directions and velocities,

turbulent flow is found at

distal to stenosis

Reynolds number

predicts turbulence

Reynolds number =

> 2000 = turbulence

Reynolds number =

[average flow speed x tube diam x density ] / viscosity

2 patterns of pulsatile flow

high res, low res

organs supplied by low res

essential for life, need constant perfusion

RI =

A-B / A

PI =

A- B / mean

S/D

PSV /EDV

BOUNDARY layer

layer of fluid in which the surface of the vessel wall has exerted its influence by means of viscous drag

velocity at boundary layer

0 at wall

boundary layer separation

free boundary between layers of fluid moving in opposite directions, can be found in carotid bulb

flow preceding stenosis

slows down

flow at stenosis

jet

flow after stenosis

turbulence

flow further after stenosis

tardus parvus

Reynolds

effects of change of diameter and speed on fluid flow patterns

most common variant of aortic arch

bovine arch = common origin of brachiocephalic/innominate and LCCA

Hemodynamics Flashcards

(77 cards)