Cardiovascular Biomechanics Flashcards
What do arteries do?
carry oxygenated blood to
the organs and cells of the body
What are the two categories of arteries?
large elastic arteries and muscular arteries
Why does a blood vessel stiffen as you stretch it?
stiffer components like collagen fibers begin to engage and bear the load. Collagen is much less elastic than elastin, causing the vessel to resist further deformation more strongly, making it feel “stiffer.”
straightening of fibers leads to a progressive increase in stiffness as more fibers align to bear the tensile force.
What are the conditions for Poiseuilles law?
➢ Newtonian fluid (Does not exhibit a change in viscosity with changes in shear-rate)
➢ Laminar flow
➢ Rigid wall
➢ Steady flow
➢ Cylindrical shape tube
➢ Fully developed flow
What are some observations on Poseuilles law?
For a given pressure drop, a 1% change in vessel radius will cause a change in blood
flow to the power of 4.
blood pressure is controlled by vessel radius.
Hypertension (high blood pressure) can be caused by narrowing of blood vessels
Blood pressure can be reduced by relaxing the smooth muscle tension that controls
radius.
y reduce blood viscosity and thereby resistance to blood flow by
haemodilution, sometimes in surgery.
what is autoregulation of blood flow?
tendency for blood flow to remain constant
in the face of changes in local arterial pressure to the organ. Changes in the chemical or
mechanical environment can affect muscle tone, which in turn controls the vessel diameter and flow resistance.
What is the cost function?
sum of the rate at which work is done on
the blood and the rate at which energy is used up by the blood vessel. - design parameters chosen so cost function minimised
What is arterial flutter?
due to low pressure the walls can cave in
What is an aneurysm?
localised dilation of the blood vessel leading to a rupture of the vessel wall. caused by the weakening of the arterial wall where a bulge occurs and the lumen cross section increases
Effect of velocity and pressure on eachother
velocity reduces = pressure increase.
when blood flow velocity increases, high pressures can develop and rupture vessels
What is atherosclerosis?
a form of arteriosclerosis (artery + skleros,
hard) in which deposits of plaque containing cholesterol, lipoid material and lipophages are formed within the intima and inner media of arteries.
non-uniformly distributed in the body.
It generally occurs at certain points on the arterial tree.
Coincide with regions that have:
➢ Complex geometry
➢ Large Reynolds number
➢ Lower than average wall shear stress
