Hemodynamics Flashcards
what are the 2 types of directional flow
forward and reverse flow
what is hemodynamics
blood movement
study of blood flow or the circulation
what is circulation
flow of blood through a closed system
describe arterial system
multibranched elastic conduit that carries blood away from the heart
the heart is the pump through contractions and relaxations
when the heart contracts, the intended flow is forward into the _____ and ______ artery
aorta and pulmonary artery
blood flow is in _____
ability to do _____
motion
work
what is conservation of energy
energy is never lost only converts to another form
potential - _____ energy
kinetic - _____ energy
total energy = _____ + _____
resting - static
motion - dynamic
potential + kinetic
what is work
amount of energy transferred over time
units - joules
what is power
concentration of force per unit area
force behind fluid flow
what is hydrostatic pressure
pressure exerted by a fluid due to its weight or force per unit area
measured related to the heart
units - mmHG
factors of hydrostatic pressure
height of the column of blood
density of the fluid
force of gravity
what is energy or pressure gradient
pressure difference in order for blood to move
**flow is from high to low pressure
pressure in the left ventricle rises and blood is ejected out of the _____ valve into the _____
aortic valve
aorta
what is stroke volume
amount of blood ejected
equal to the difference between end-diastolic volume and end-systolic volume
heart pump generates _____ to move the blood
pressure (potential energy)
pressure gradient is the same as pressure _____
difference
**necessary to maintain flow
greater the pressure gradient, the _____ the flow rate
greater
loss in flow is due to…
friction
resistance
greater the resistance, the _____ the flow
lower
what is viscosity (thickness)
the resistance to flow
units - poise or kilogram per meter second
what is laminar flow
normal flow
layers with the highest velocities in the center stream
types of laminar flow
parabolic - shape of a bullet
plug - same velocity
energy is lost in the form of _____ due to friction
heat
what is Poiseuille’s Law
flow rate through a cylindrical tube is directly proportional to pressure gradient, the driving pressure along the tube, and the 4th power of the radius
flow is inversely proportional to length of the tube and viscosity of the liquid
Poiseuille’s Law - 3 primary factors that determine the resistance to blood flow within a single vessel
vessel diameter (radius) - MOST IMPORTANT
vessel length
viscosity of the blood
Poiseuille’s Law relationships:
pressure and flow rate && diameter and flow rate
directly related
Poiseuille’s Law relationships:
length and flow rate && viscosity and flow rate && resistance and flow rate
indirectly related
Poiseuille’s Law
radius decrease, resistance _____, flow rate _____
viscosity increases, resistance _____, flow rate _____
length increases, resistance _____, flow rate _____
increases, decreases (for all 3)
resistance of the arterioles accounts for about _____ of the resistance in systemic circulation
half
what is Bernoulli’s Principle
velocity and pressure are inversely related
high velocity - low pressure
low velocity - high pressure
relationship in a stenosis
peripheral resistance
low resistance flow - _____ diastolic flow
high resistance flow - _____ diastolic flow
high
low
**look at images on slide 35
stenotic vessel might present with what
reduction in volume flow
bruits
spectral broadening
what are the 2 types of flow
laminar - parabolic or disturbed
turbulent - chaotic or eddies
what is Reynold’s
shows turbulance
***above 2000 = turbulent flow
what can increase the Reynold’s number
increased flow speed and vessel radius
what is pulsatile flow
non steady flow with acceleration and deceleration over the cardiac cycle
_____ or _____ produces disturbed or turbulent flow
narrowing or stenosis
what is the continuity rule
flow rate must be constant
flow speed _____ at a stenosis and turbulence can occur _____
increases
distally
what is bruit
sound produced by turbulence
what is occlusion
blocked vessel - no flow - no sound (bruit)
at the stenosis the pressure is _____…
less
pressure difference - fluid _____
accelerates
decreased pressure in high flow speed = _____ effect
Bernoulli
what are the 3 waveforms
triphasic
biphasic
monophasic
what is triphasic
high pulsatility
sharp upstroke in systole
forward flow
what is biphasic flow
moderate pulsatility
what is monophasic flow
low pulsatility
broad systolic peaks
