Hemodynamics Flashcards
What is the flow equation?
Q=A (v)
What type of flow does the below describe?
Q= Q1= Q2= Q3…..
Flow in a series….it is constant
What type of flow does the below describe?
Q= Q1+ Q2+ Q3…..
Flow in parallel…it is additive
What is blood flow through an INDIVIDUAL organ equivalent to?
It is equivalent to flow through a SERIES
Can there be differences in reistance in different organs?
Yes, there can be dramatic differences
What is the total peripheral resistance (TPR)?
It is the overall resistance to flow throughout the circulation
How are organs arranged in terms of flow?
In a parallel network (note however, the flow through an individual organ is a series flow)
How does the resistance of each organ contribute to the TPR?
additive, but in an inverse relationship
What do pressure differences between the aortic valve and the RA come from?
frictional losses from circulation
MAP=
CO x TPR
CO is approximately equal to what?
Q (resistance)
TRP=
P aorta - P r. atrium
_______________
CO
Resistance decreases in what condition and increases in what other condition?
Decreases= during exercise Increases= during hypertension
What is the critical parameter that characterizes flow?
The Reynolds Number
What does the Reynolds number take into account?
disruptive forces (numerator) and cohesive forces (denominator)
What is viscosity?
A measure of intermolecular attractions in the liquid
It determines the stepness of the velocity gradient
When does laminar flow break down?
When velocity reaches a critical point (exceeds the Reynolds number)…resistance increase
In laminar flow, what is flow proportional to?
Change in P
For the same Change in P, which has more flow….turbulent or laminar?
Laminar Flow
Which type of flow is silent and which flow generates a sound?
Silent= Laminar Sound= Turbulent
What are turbulent flow sounds called?
Auscultory sounds
What are murmurs?
audible sounds due to vibrations in heart or vessel walls
What is an “innocent” cyctolic murmur?
occurs when cardiac output increases during excercise which causes turbulent aortic flow during systole
What is the gravitational pressure equal to?
(density) (gravity) (height)