21 Overview of Circulation and Hemodynamics Flashcards
Is blood pressure higher in the arteries or in arterioles?
arteries
What vessels exhibit compliance and elasticity in order to reduce pulsatility?
aorta and large arteries
What vessels are the major site of vascular resistance?
arterioles
What vessels have the largest total surface area
Capillaries—for exchange
What vessels are the most compliant or distensible and as such act as the blood volume store?
Veins
What is Poseuille’s Law for Q (blood flow)?
Q= (Pi-Po)/R
[P=pressure, i=inlet, o=outlet, R=resistance]
Resistance in a blood vessel is proportional to what 2 characteristics?
length and viscosity
What is the most important determinant of resistance?
Radius (inversely proportional raised to 4th power)
Does an increase of RBC raise or lower blood viscosity?
raise
Blood flow to a particular organ is equal to? (equation)
(Q)CO=MAP/TPVR
What are the two ways to increase mean arterial pressure (MAP)?
- Increase Cardiac Output
2. Increase total peripheral vascular resistance
What are two ways to decrease mean arterial pressure?
- Decrease cardiac output?
2. Decrease total peripheral vascular resistance
What would cause a decrease in flow but an increase in blood pressure?
greater resistance
The slope of the flow/ pressure curve is inversely related to what?
resistance
How do you calculate total resistance for a group of resistances in series?
add them
How do you calculate total resistance for a group of resistances in parallel?
reciprocal of total = sum of reciprocal of individual resistances
What results from the fact that most resistances in circulation are in parallel?
total peripheral vascular resistance is much less than vascular resistance within a specific vascular bed.
What type of blood flow is streamlined, regular, orderly and has parallel layers?
Laminar flow
Where is blood flow the fastest in a vessel?
In the center (leading edge looks like a parabola)
What type of blood flow is disorganized with eddies and multi directional?
Turbulent flow
What does high velocity, increased density, large diameter and low viscosity do to blood flow?
they all increase turbulence (vice versa holds true to)
Where is most turbulent flow found within the body?
Ascending aorta, main pulmonary artery, just distal to stenosis
Very turbulent flow can be diagnosed by hearing what?
bruits in arteries and murmurs in heart valves
