L.10,16,20 Equations Flashcards
Ventricular ejection fracion
difference between end diastolic volume and systolic volume ) divided by end diastolic volume times 100
What is stroke work (pressure per volume work done during each cardiac cycle)
SW= MAP x SV
What is Q (flow rate)= mL min-1
Also known as CO
Q= pressure difference between two points/ resistance or CO= HR x SV
What is the effect of parallel arrangement of vessels on arterial pressure
Parallel arrangement of many vessels means changing the resistance to a specific vascular bed has little effect on arterial pressure but greatly affects the downstream flow to particular vascular beds.
What is MAP usually and MVP
100 mmHG for MAP
MVP is usually 0mmHg but in HF it can be higher.
When you increase resistance in the periphery what effect does that have on the flow locally and totally
Downstream flow to the vascular bed is affected, but the total amount of flow is unchanged as restricting one bed just means that a proportionate amount is spread throughout the rest.
There is upstream increase in pressure in order to maintain flow.
What is blood flow and the normal Q (CO)
The quantity of blood that passes a given point in circulation in a given period of time.
5L/min
what does poiseuilles equation assume and what is different with the body
There is steady laminar flow (in body there is pulse but still high enough flow to be ok)
It is a rigid straight tube: (branched arterial system with compliance)
- Newtonian fluid : (can change)
What factors of resistance does poiseuilles equation talk about
vessel radius: Q inversely to r^4
viscosity : Q inversely to viscosity
What is shear stress and its effect on endothelium
As flow increases (blood pressure) the shear stress (distortion) on endothelium increases causing them to release NO which diffuses to smooth muscle cells for vasodilation. This allows more flow through helps to reduce shear stress.
However potentially leads to endothelial damage-> artherosclerosis and thrombosis
What factors determine turbulent flow => there is not efficient increase in flow when there is increase with pressure
High fluid density
Large tube diameter: more space
High flow velocities : past narrowing/ abrupt variations in tube dimension
Low fluid viscosities: flow quicker.
What is Reynolds number equation (dimensionless) , purpose and its critical value
It is Prediction of turbulent flow.
Re= (density x average velocity of flow x Diameter ) / viscosity
Turbulence is when Re > 2000-3000
What are murmurs
Turbulent blood flow could be caused by valve disease or stenosis in the blood vessels
What is mean systemic filling pressure and equation
The pressure in the system when CO is zero.
Change in pressure = change in volume/ capacitance
What is the normal range for heart rate
60-100 bpm
<60 = bradycardia, >100= tachycardia
