# Total Peripheral resistance and dBP / sBP Watch

1. I know that a HIGH TPR leads to a HIGH diastolic pressure but I do not understand why? I was also hoping someone could enlighten me (and explain to me) the relationship between sBP (systolic BP) and TPR. Thank you
2. Peripheral resistance is how much resistance there is against blood flow in the peripheral vascular system. It's increased by the peripheral blood vessels contracting: can you think why a more contracted blood vessel would lead to a higher diastolic blood pressure?
3. (Original post by Hype en Ecosse)
Peripheral resistance is how much resistance there is against blood flow in the peripheral vascular system. It's increased by the peripheral blood vessels contracting: can you think why a more contracted blood vessel would lead to a higher diastolic blood pressure?
Well I know that diastolic bp is the lowest pressure following a systolic contraction. I would have thought that if resistance increases the systolic bp decreases more quickly --> lower diastolic bp. This is why i am confused.
I can imagine, now you say that, that if TPR is higher than systolic BP would be higher because the LV has a larger after-load against which it has to work. so systolic blood pressure should increases with TPR. but I still don't get why dBP increases with TPR
thanks
4. I am also slightly confused as to why VENOconstriction decreases TPR.
TPR = (mean arterial pressure - venous pressure) / CO
this equation seems to be saying that increased venous pressure (venoconstriction) = decreased TPR
How is this true?
5. (Original post by jsmith6131)
Well I know that diastolic bp is the lowest pressure following a systolic contraction. I would have thought that if resistance increases the systolic bp decreases more quickly --> lower diastolic bp. This is why i am confused.
I can imagine, now you say that, that if TPR is higher than systolic BP would be higher because the LV has a larger after-load against which it has to work. so systolic blood pressure should increases with TPR. but I still don't get why dBP increases with TPR
thanks
I'm not sure why you think it'd lead to systolic blood pressure "falling" further. I think the confusion is coming in the way you think of diastolic blood pressure. dBP is the blood pressure while the heart is in diastole, such that there is no force being generated by the cardiomotive flow of blood. Pressure is force exerted over an area, so when we have a smaller blood vessel (due to vasoconstriction) with the same amount of blood trying to get through, there's higher pressure in the vessel. It's the same with dBP, we have the same amount of blood "relaxed" in the constricted vessel, leading to a higher diastolic blood pressure.

(Original post by jsmith6131)
I am also slightly confused as to why VENOconstriction decreases TPR.
TPR = (mean arterial pressure - venous pressure) / CO
this equation seems to be saying that increased venous pressure (venoconstriction) = decreased TPR
How is this true?
Venous pressure is so low anyway that constriction of deep veins doesn't do much to change pressure or resistance. But our venous system contains most our blood in what's called the "venous reserve", so that when our veins constrict what actually happens is there is improved blood flow through the venous system because the constriction "squeezes" the blood out and back to the heart. This increases venous return, increasing preload, and increasing CO. So by that equation, it leads to decreased TPR.

This is the "theoretical" basis, of course, but the pressures we're dealing with here are so low that I don't think it has that effect in reality.
6. With regard to the dBP...that is a much more sensible way to look at it. my lecturer made it so much more confusing..thanks

with regard to TPR...that's quite a clever way of looking at it. thanks

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