CPR Circulation and Hemodynamics Flashcards
Which vessels have the greatest cross sectional area? Second greatest?
Capillaries
Veins
Which vessels hold the greatest blood volume?
Veins (~65%)
What does constriction of veins do?
Pushes blood into arteries to increase BP, doesn’t change resistance that much
What does constriction of arteries/arterioles do?
Doesn’t shift much blood over to veins but DOES increase resistance
What is the equation of velocity of blood flow?
V = Q/A velocity = flow/area
What is the relationship between blood flow, pressure, and resistance?
Q = delta P/R flow = pressure gradient/resistance
How are flow and resistance related?
Flow is inversely proportional to resistance
How is vessel radius related to resistance?
R = (8nl)/pi r^4) R = resistance r = vessel radius (one of main ways to regulate BP)
How is vessel length related to resistance?
As length increases, resistance increases (in parallel circuits total resistance decreases)
What is laminar flow?
Even blood flow, not turbulent
What is Reynolds number?
Nr = pdv/n p= density of blood d= diameter of vessel v= velocity of blood n= viscosity of blood
If Nr is >2000 then transition from laminar to turbulent flow
What is a bruit
Turbulent flow
What is compliance of blood vessels?
How easy it is for a vessel to expand, opposite of elasticity. Higher elasticity = less compliance
Which vessel has the highest compliance?
Veins - lowest elasticity
Arteries - lower compliance
Old arteries - very low compliance
What does smooth m contraction in veins do to compliance?
Decreases compliance, causes increase in pressure and shift of blood from veins to arteries
