L9- vascular resistance Flashcards
what are elastic arteries
larger vessels that has SM and elastic fibres in them
what is the driving pressure in the CVS
arterial blood pressure which is the ejection of blood from the ventricle leading to a pulsatile pressure in the aorta and large arteries
functions of elastic arteries (EA)s
- dampening pulsatile pressure for continuous flow into the circulation
- ensures that the BP is maintained during diastole so basically act as tubes for filling of blood
what is the pulse pressure
difference between SP and DP (SP-DP)
- both pressures creates the pulse pressure wave starting from DP at 80mmHg to SP at 120mmHg
how to work out mean ABP
((SP-DP)/3) +DP
what happens to the aortic wall during systole and diastole
- during systole, the wall distends to accommodate the blood flow so the energy converted to elastic energy
- the aortic wall recoils during diastile to propel the blood forward, energy is then released
why does the pressure wave drop as it travels from aorta all the way to veins
- due to diff R in the diff vessels
- the pressure waves decreases as it moves away from the origin
describe the effect of age on pulse pressure
the elastin degenerates and the collagen becomes more prominent so the arteries stiffen
- leads to increases SP and decreased DP
- the pressure wave becomes longer in height
what factors determine the ABP (driving force for blood flow)
- blood vol in the arterial system (CO)
- resistance to the blood flow (TPR)
how to work out ABP (NOT mean ABP)
CO X TPR
factors determining SP
- SV
- aortic distensibility
- ejection vel
- DP of the previous beat
what factors determines DP
-by the arteroilar R and HR
what factors determine the resistance to the blood flow
- vessel length
- blood viscosity
- radius
- leading to poiseuille’s eqn
what happens to the flow when there’s vasodilation
- increases the flow
what happens to the flow when there’s vasoconstriction
-decreases the flow
