Circulation and Hemodynamics

Question 1

Hemodynamics of Arteries

Answer 1

High pressure

Question 2

Hemodynamics of Arterioles

Answer 2

Moderate pressure

smooth muscle walls can contract to control flow by changing resistance

Question 3

Hemodynamics of Capillaries

Answer 3

Large cross sectional area
single endothelial lining to allow for nutrient, waste and gas exchange
blood moves very slow through here

Question 4

Hemodynamics of Veins

Answer 4

Low pressure
Large volume
can contract to move blood to arterial side to increase Blood pressure

Question 5

how will the resistance change if there is a constriction of veins to move blood to the arteries

Answer 5

wont change the TPR very much due to the large area of veins that a small contraction will lead to alot of blood movement

Question 6

Where is 65 percent of the blood located through its circulation

Answer 6

the Veins

Question 7

what happens if their is constriction of the arteries

Answer 7

Not much volume change
but an increase in resistance

works inversely to Veins

Question 8

equation for the velocity of blood

Answer 8

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

Question 9

how does the body alter what organ systems recieve blood

Answer 9

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

Question 10

What is the equation/relationship between Blood flow, pressure and resistance

Answer 10

Q (flow) = Change in pressure (or gradient)/R (resistance

this relates to

CO = (arterial pressure-venous pressure)/ TPR

Question 11

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

Answer 11

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)

Question 12

how are resistances addded in series or parallel and how do they affect the overall resistance

Answer 12

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

Question 13

what is the significance between laminar flow and turbulent flow

Answer 13

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

Question 14

what can turbulent flow lead too

Answer 14

Sounds (bruits) and lesions (arteriosclerosis)

Question 15

what is compliance? and what does high vs low compliance mean

Answer 15

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

Question 16

how is compliance and elasticity related

Answer 16

they are inversely related

c=change in V/change in P

e=change in P/change in V

Question 17

how does atherosclerosis affect compliance

Answer 17

decrease in compliance

Question 18

how does smooth muscle contraction of veins affect compliance, blood volume, and pressure

Answer 18

Decrease in compliance of Vein
Decrease in blood volume in the vein
Increase of blood in artery
increase of pressure in artery

Question 19

how is pressure in the Aorta, Large arteries, and small arteries different then pressure in the arterioles cappillaries and veins

Answer 19

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

Question 20

where is pressure the highest and lowest and where is the biggest drop off

Answer 20

highest: Aorta
lowest: veins
biggest pressure change: arterioles

Question 21

how to calculate the pulse pressure and the mean pressure

Answer 21

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

Question 22

what is the difference between the pulmonary and systemic blood flows

Answer 22

same amount of blood flows through each system but

pulmonary has much lower pressure because of much less TPR

Question 23

since pulse pressure is dependent on the arterial compliance, what would happen if compliance decreased, if stroke volume increase, and increase resistance

Answer 23

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

Question 24

significance of calculating the left atrial pressure and how is it done?

Answer 24

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