BMS10-1022 Physics of Blood Flow Flashcards
Where does the right heart pump to?
Lungs
Which circulation has low resistance and pressure?
Pulmonary
What is the average SV?
70-80ml per beat
What is the average CO?
5 litres per minute
Describe the CVS
LV Large arteries Arteries Arterioles Capillaires Venules Great veins Right ventricule Arterioles Capillaries Veins Venules
What kind of pressure is arteriole?
Pulsatile
What mainly causes TPR?
Small arties and arterioles
CO= (2)
MAP/TPR
SV x HR
How do you calculate ejection fraction?
SV/EDV
What does TPR determine?
Pressure load on left heart (afterload)
What does the CVP determine?
Filling pressure (preload)
MAP=
CO x TPR
What is darcys law?
Flow = (P1-P2)/R
What does the law assume? (2)
FLuid is incompressible and Newtonian and flow is laminar
R=
8 x viscosity x length / pi x r to the power of 4
What happens when these 2 equations are combined?
(p1-p2) pi r to the power of 4 / 8VL
What factor is the most important?
Diameter as it causes a large change in resistance therefore flow unlike length and viscosity
What can increase viscosity and what does this mean?
RBC and flow is reduced
What is the fahraeus lindqvist effect?
Reduces viscosity by getting the cells in the axial stream as they move faster here as there is drag at the sides
Which type of type is likely to experience turbulence?
Large tubes
What 3 factors may lead to turbulence
Sharp edges
High velocity
Branch point
What is turbulence?
Disruption in laminar flow increasing resistance and vibrations
What is Reynolds number?
Indicates if blood flow is laminar or turbulent
V x D / V
What is ohms law?
Current = V/R
How do you calculate R in series?
Add them up
How do you calculate R in parallel?
1/total = 1/R1 + 1/R2 etc
Conductance=
1/R
Where is series?
Terminal artery and arteriole
Where is parallel?
Capillary
Why is resistance high in series?
All resistances add up
Why is resistance low in parallel?
Conductances add up
What does it mean if a pressure difference remains constant?
It can control its own flow by constricting and dilating
