Arterial System Flashcards
Main constituents of a vessel wall
Elastin and Collagen
Elastin
Highly deformable with low Young’s module
Ratio of Elastin and Collagen
Principal determinant of overall elastic behavior of a vessel.
Endothelium
Basement membrane and elastic lamina, where endothelial cells are attached.
Arteries diameter
Arterial diameter can vary by 10%
Removal of elastin
Removal of elastin = stiffening
Removal of collagen
= elastic behavior
Systolic pressure
Systolic pressure increases with distance from the heart. Diastolic doesn’t
Ejection of blood
Ejection of blood leads to expansion of the aorta to accommodate the ejected volume.
Increase in circumference of artery?
Increase in circumference increases tension in the arterial wall which increase the pressure within blood.
PWV
Pressure wave propagation speed. Changes depending on the distance from he heart.
PWV estimation
The difference in arrival time of the pressure wave at different points in the arterial tree
Flow
Determined by Reynolds number
Reynolds number
Decreases with distance from the heart.
Systolic phase has turbulent flow and the remainder of the arterial circulation is laminar
Axial flow
Flow in a long straight pipe will become axial after certain distance
Rotation flow
Caused in a curve pipe or branching, also twisting of ventricle during contraction
Symmetric velocity profile
Long straight tube
Asymmetric velocity profile
vessel is curved or immediately downstream
Arterial wall forces
Pressure and Shear Stress
Arterial wall
Is able to sense forces and adjust in order to compensate for other forces
Cyclic variation in pressure
Leads to variation in a diameter and circumference of the artery, trying to reach equilibrum
Murray’s Law
Number of vessels increases with each branching and diameters decrease
Arterial system design
Is design so that the heart needs to expend the minimum amount of effort to pump blood.
