Circulation and Hemodynamics Flashcards
Hemodynamics of Arteries
High pressure
Hemodynamics of Arterioles
Moderate pressure
smooth muscle walls can contract to control flow by changing resistance
Hemodynamics of Capillaries
Large cross sectional area
single endothelial lining to allow for nutrient, waste and gas exchange
blood moves very slow through here
Hemodynamics of Veins
Low pressure
Large volume
can contract to move blood to arterial side to increase Blood pressure
how will the resistance change if there is a constriction of veins to move blood to the arteries
wont change the TPR very much due to the large area of veins that a small contraction will lead to alot of blood movement
Where is 65 percent of the blood located through its circulation
the Veins
what happens if their is constriction of the arteries
Not much volume change
but an increase in resistance
works inversely to Veins
equation for the velocity of blood
V=Q/A
velocity is equal to the flow of blood over the area
can be used for a single vessel
or can be used for cross sectional area of parallel circuits
how does the body alter what organ systems recieve blood
can be changed through constriction and resistance to alter the percentage of blood flow to specific organs
for example during excersise body moves more blood to the muscles
What is the equation/relationship between Blood flow, pressure and resistance
Q (flow) = Change in pressure (or gradient)/R (resistance
this relates to
CO = (arterial pressure-venous pressure)/ TPR
how to determine the resistance to blood flow for a section of vasculature, what is the name of this law and how can it be altered
Poiseuille’s Law calculates resistance through a section of vasculature
R=(8nl)/(pi(r^4))
n=viscosity (can change via proteins or number of bloodcells(doping))
l=length of vesicle
r=vessel radius (can change via constriction or dilation to change resistance and ultimately BP)
how are resistances addded in series or parallel and how do they affect the overall resistance
if Vasculature resistance is in a series (artery to arteriole to capillary) they are added together
-total resistance will increase in series
if vasculature is in parrallel (blood splits to different systems) they are added by 1 over the resistance
-total resistance will decrease in series
what is the significance between laminar flow and turbulent flow
laminar flow = smooth flow with high velocity in center and slower velocity on the side in a tube, there is no back flow or blockage
turbulent flow: when velocity is high, cross sectional area high, viscosity is low blood flow can become turbulent and cause back ish flow and messy flow
what can turbulent flow lead too
Sounds (bruits) and lesions (arteriosclerosis)
what is compliance? and what does high vs low compliance mean
Compliance is how easy it is to cause a vessel to expand
-how much does the vessel expand in response to a given change in lumen hydrostatic pressure
C=change in volume/change in pressure
high compliance = balloon for party (easy to expand) low compliance (balloon for animal) hard to expand
how is compliance and elasticity related
they are inversely related
c=change in V/change in P
e=change in P/change in V
how does atherosclerosis affect compliance
decrease in compliance
how does smooth muscle contraction of veins affect compliance, blood volume, and pressure
Decrease in compliance of Vein
Decrease in blood volume in the vein
Increase of blood in artery
increase of pressure in artery
how is pressure in the Aorta, Large arteries, and small arteries different then pressure in the arterioles cappillaries and veins
in the Aorta, Larger arteries and small arteries the pressure will pulsate due to compliance and distention during ejection and diastole to store and dissapate the energy
the largest pulsate occurs in the Large arteries due to an echo of pressure effect from the small vessels
where is pressure the highest and lowest and where is the biggest drop off
highest: Aorta
lowest: veins
biggest pressure change: arterioles
how to calculate the pulse pressure and the mean pressure
pulse pressure = systolic-diastolic (usually 40)
mean pressure = diastolic + 1/3pulse (usually 93.3)
this is because the cardiac cycle spends more time closer to Diastole than systole
what is the difference between the pulmonary and systemic blood flows
same amount of blood flows through each system but
pulmonary has much lower pressure because of much less TPR
since pulse pressure is dependent on the arterial compliance, what would happen if compliance decreased, if stroke volume increase, and increase resistance
a decrease in compliance would cause an increase in pulse pressure, this would also cause systolic pressure to increase, and may cause diastolic pressure to decrease
increased stroke volume: decreases resistance and increase compliance
increase in resistance (arteriosclerosis): decrease in compliance and increase in pressure
significance of calculating the left atrial pressure and how is it done?
done by pulmonary wedge pressure by putting a balloon in a Pulmonary artery block it and then to determine its pressure since it should be similar to the atrium
this is important because in cardiac failure when the left ventricle stops pumping it leads to an increase of pressure in the left atrium
determining its pressure can help doctors determine the significance of the heart failure
