3-Hemodynamics Flashcards
laminar flow
streamlined, efficient flow
-parabolic bc slower/more friction/resistance close to vessel wall + highest velocity in middle
turbulent flow
irregular eddy currents with more shear stress on endothelial cells
-more energy to move blood
-thrombi more likely to devel
most important factor driving turbulent flow
velocity
blood flow = cross section area x velocity
atherosclerosis
narrowing vessels from plaque build up
-from turbulent flow
-hear bruits
law of laplace
wall tension = (transmural pressure x vessel radius) / wall thickness
inc wall tension from
transmural pressure + radius
thicker walls = ? tension
wall thickness dec wall tension bc better able to withstand
wall tension balanced by
elastic + smooth muscle in vessels
if mismatch then rupture/aneurysm
aneurysm
wall tension inc as vessel radius inc + transmural pressure inc = rupture
can be undetectable with just inc wall tension and radius until the pressure maximizes
most prominent effect on flow
vessel radius
artery structure
large lumen + thick walls
arterioles structure
small lumen + thick innvervated wall
capillaries structure
smallest lumen + very thin walls (1 cell)
venules structure
small lumen + thin walls
vein structure
large lumen + thick walls
arterials as resistors
small changes in volume = large shift in pressure
venous as capacitors
small changes in pressure = large shift volume
venous compartment
largest volume of blood
-pressure direct to blood amount
if veins constrict then more vol pushed into circulation back to heart (symp stim)
flow =
change in pressure / resistance
direct relation, move same direction
if constant flow then ? velocity
velocity dec as total cross sectional area inc
why aorta has highest velocity bc smallest total cross section
where pressure drop is greatest
across arteriolar compartment, corresponds with inc resistance
arteriolar vasodilation = ? flow
inc capillary pressure and blood flow
arteriolar vasoconstriction = ? flow
dec capillary pressure and blood flow
-inc afterload in LV
resistance differences
L and R
left heart = systemic circulation resistance is 1 TPR
right heart = pulmonary circulation resistance is 0.1
total resist of systemic circ x10 higher than pulmonary
velocity trends
- highest in large arteries
- drops dramatically as approach capillaries
- rise slowly towards veins
volume trends
- highest in capacitor vessels of veins
- lowest in high resistance structures (arterioles and caps)
pressure trends
- highest in arteries and arterioles
- lowest in veins
resistance trends
- peaks in arterioles
- low in arteries, caps, and veins
