stress-relaxation and myogenic mechanism

[ATPenergy]

When blood volume in vessel increase
stress-relaxation: vessel wall stretch
myogenic mechanism: smooth muscle in vessel wall contract
so What situations do each of them happen?😕

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[ArcGurren]

I don't really understand your question.

The myogenic mechanism explains why you have reflexive vasodilation in certain organs when there's low blood flow (like in hemorrhagic shock your brain would vasodilate to keep the blood moving at a constant flow as much as possible to everywhere in your brain) - when there's a high arterial pressure it vasoconstricts to maintain a constant flow. => remember, Q = P/R, so this makes sense mathematically (increase P, increase R to compensate, etc).

 

[ATPenergy]

yes but about stress relaxation
When there's high blood flow, stress relaxation will cause blood vessels relax so it's opposite things that myogenic mechanism cause (blood vessels contract)

 

[coralis]

It is not so much a specific situation, but it specific to compliance of the tissue. It is a way to control pressure. More or less they both work in tandem in the aorta (if that's the scenario you were looking at). See http://www.cvphysiology.com/Blood Pressure/BP027.htm maybe this will help

 

[coralis]

Remember the myogenic mechanism is there to prevent damage due to the relaxation in the aorta. For example if the aorta were to accommodate and keep stretching with every increase in blood volume, we wouldn't be able to maintain proper flow, it would just pool in the aorta. Thus reaction to stretching is contraction.