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 Q to mash/retroviridae/namf/lyspro/anyone  



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Author9 Posts
  #1

hi guys,

I have seen that many people really help each other a lot here.I will be grateful if someone can please explain the following concept to me.;;
kaplan notes [physio]says that decrease in each of these=> vessel compliance;heart rate;strokevolume;total peripheral resistance;=>decreases diastolic pressure.can someone please explain the concept behind how these factors reduce diastolic pressure.thanx in advance for u'r time and patience. <help>




  #2

Diastolic pressure is dependent upon TPR, so if it decerases DP falls..thats a given. HR decrease will cause less waves transmitted through the vascular system and DP will decrease initially, untill sypath kicks in. Stroke volume has filling affect on vessels, so if it decreases, less blood is present in arterioles at end systole, so DP falls.
However, decrease in complience of vessels should increase DP. The less complience vessel has, the more pressure it exerts upon the filling substance, in this case blood. So in complience falls-->DP rises.
Hope this helps.


  #3

Let me ponder this and answer your q after I swim so I can give it 110%


  #4

hi mdwannabe,

thanx for u'r response.i too thought that decrease in compliance should increase DP.but other than the kaplan notes i even read this in another website where it says that as the aortic pulse moves away from the heart,systolic pressure increases and diastolic decreases due to decrease in compliance of the vessels as we move peripherally.it was pretty confusing to me. roll ? anyways i am hoping that one of our friends here can help clear these things.
also there is one more thing that i noticed.whenever there is decreased stroke volume,both DP nd SP should decrease.but when heart rate decreases DP decreases but SP increases [due to increased stroke volume ] hence there is wide pulse pressure].am i right?

thanx mjl1717.waiting for u'r response.


  #5

On second thought and I dont want to be redundant-Id say mdwannabe did a pretty good job with the original q.


  #6

i guess the only way i can understand this thing is if you have a decrease in compliance then when there is a "systolic" passing of the blood, the pressure on the walls would increase....but the wall wouldn't stretch because it is less compliant. and when the "diastolic" blood goes through the same vessel there would be little "recoil" from the systolic passing... so the the pressure goes down. think of it as a steel tube with systolic and the diastolic blood flowing through it, as opposed to a dynamic tube that adjusts it's diameter to the the amount of blood in the tube.


  #7

adeelmd, that is actually totally right on. most of the compliance in the system is in the large arteries. when compliance goes down, you have increased systolic pressure from pushing into them and lower diastolic from rapid emptying.

i think tpr works differently because most of it happens at the arterioles and traps blood backwards.


  #8

THANX adeelmd and blue dusk.I really appreciate the help.good luck.


  #9

THANX adeelmd and blue dusk.I really appreciate the help.good luck.





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