Circulation And Hemodynamics Flashcards
What is the site of the highest resistance and largest drop is pressure?
Arterioles
Composition of capillaries
Single layer of endothelial cells surrounded by basal lamina
How is perfusion of capillaries determined?
By metabolic needs of the tissue and the tone of the arteriolar smooth muscle
Velocity of blood flow
V=Q/A
Speed at which blood travels
Flow=speed and number of blood traveling
Flow equation
DeltaP/R
Poiseuille’s law
(8ln)/(piR^4)
Series resistance
Resistance is the sum of the forces
Parallel resistance
Resistance is 1/sum of the resistances and is lower than all individual resistances
Bruits
Heard when turbulent flow occurs in an artery or other vascular channel
Reynold’s number
Nr=(pdv)/n
Density
Diameter
Velocity
Viscosity
<2000 predicts laminar flow while >2000 predicts turbulent flow
Mean arterial pressure
2/3 DBP + 1/3 SBP
DBP + 1/3 pulse pressure
Arteriosclerosis
Plaque deposits form in arterial walls - decreases diameter and compliance of vessels, increases SBP, pulse pressure, and MAP (no large influence on DBP)
Lipid soluble microcirculation
O2, CO2. Driven by partial pressure gradient for that gas - also determined by the surface area of capillaries.
Water soluble microcirculation
Ions, glucose, AA
Diffusion doesn’t occur well. Limited movement between clefts of endothelial cells. Limits SA available for movement of molecules.
Osmosis of microcirculation
V important.
Driven by hydrostatic and osmotic pressure differences btwn lumen of vessel and interstitial space