hemodynamics

Question 1

in terms of venous and arterial sides, what serve as resistors and what serves as capacitors

Answer 1

• resistors- arterial “pressure effects”

- capacitors- venous “volume effects” -most blood vol on ven side

Question 2

list the path of flow of blood from artery to vein and describe what type of fibers each blood vessel type has

Answer 2

artery-elastic, fibrous, endothelium and smooth muscle
arteriole-endothelium, smooth muscle
capillary-endothelium
venuole-endothelium and fibrous tissue
vein-elastic, SM, endothelium, and fibrous tissue

Question 3

blood flow vs blood flow velocity

Answer 3

blood flow- volume per time

blood flow velocity -distance per time

Question 4

equation for flow

Answer 4

• [change in pressure (difference of pressure at two ends of the vessel)]/ resistance (impediment to blood flow thru vessel)

Question 5

poiseuilles law

Answer 5

flow= (change in pressure x 3.14 x radius x 4)/ 8(viscosity) (length)
viscocity =HCT

Question 6

define laminar flow

Answer 6

• parabolic
• flows in a concentric pattern where the inner part flows faster than the outer due to the face that the outer has contact with the edges of the vessels

Question 7

turbulent flow

Answer 7

• disorganized and inefficient flow where more work needs to go into getting blood thru the vessels
• NOISY

Question 8

korotkoff sounds

Answer 8

• what we hear when we are taking a blood pressure
• when we increase the pressure in the cuff, we are stopping laminar flow
• when we release the pressure and hear the sounds, that is turbulent flow
• when we can’t hear the sounds anymore, laminar flow

Question 9

Reynolds number
equation
what does it tell us

Answer 9

Re (turbulence) = 2(radius)(velocity)(fluid density)/viscosity

• tell us that larger vessels are more prone to turbulence
• fast fluid flow makes us more prone to turbulence
• viscous blood makes less turbulence

Question 10

critical velocity

Answer 10

-the velocity at which you will begin to get turbulent flow

Question 11

transmural pressure

Answer 11

-pressure across the blood vessel

Tension = (change in pressure)(radius)

Question 12

if you increase the radius I the vessel, what happens to tension or transmural pressure

Answer 12

-it increases because if the radius is increased, it means that it is ballooning

Question 13

how does the blood flow from the aorta to the venous system without rupturing things given that as you travel along, you get smaller diameters and weaker vessels (ie arterioles vs arterties and arterioles vs venuoles etc)

Answer 13

• we have a decrease in INDIVIDUAL cross sectional area per vessel-type but there are more of the smaller vessels so the TOTAL cross sectional area is larger.
• this allows for the pressure to evenly distributed
• ALSO, SINCE THERE IS A LARGER CROSS SECTIONAL AREA IN THE SMALLER VESSELS, WE MUST DECREASE VELOCITY TO MAINTAIN STEADY FLOW- this is great for the vessels because it allows them to eliminate waste and absorb oxygen efficiently

Question 14

is resistance higher in a series or parallel?

Answer 14

-in a series because have to flow thru both versus having other avenues to go thru

Question 15

how do you calculate resistance in the left heart vs resistance in the Right heart?
values: 
C0 = 100 mL/sec
aortic pressure= 100
RAP (right atrial pressure) = 0
pulmonary artery pressure =15
LAP = 5

Answer 15

Flow = change in pressure/resistance therefore 
resistance = change in pressure/ flow-

Left heart:
100-0/100= 1

Right heart:
15-5/100 = 0 .1