Oh_Gee

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in hypovolemic shock, pulse pressure narrows because of a decrease in systolic BP and an increase in diastolic BP

hypovolemic shock> decreased preload> decreased cardiac output> decreased systolic BP (i get this part)



hypovolemic shock> sympathetic reflex> increased total peripheral resistance> increased diastolic blood pressure (i don't get the bolded part)

why does Diastolic BP increase?

is it because increased TPR> increased afterload> more blood remains in left ventricle after systole than normal (which means more Diastolic BP)
 
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68PGunner

Diastolic BP drops = vasodilation whereas diastolic BP increases = vasoconstriction.
 

mehc012

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in hypovolemic shock, pulse pressure narrows because of a decrease in systolic BP and an increase in diastolic BP

hypovolemic shock> decreased preload> decreased cardiac output> decreased systolic BP (i get this part)



hypovolemic shock> sympathetic reflex> increased total peripheral resistance> increased diastolic blood pressure (i don't get the bolded part)

why does Diastolic BP increase?

is it because increased TPR> increased afterload> more blood remains in left ventricle after systole than normal (which means more Diastolic BP)
Remember...in diastole, the aortic valve is closed, and therefore the diastolic BP ≠ the pressure in the left ventricle. Diastolic BP is increased literally because the resistance in the arteries is increased and...that's what you're measuring.

In systole, the aortic valve is open, aortic BP = LV pressure, systolic pressure is more the result of what the heart can generate (and if it doesn't have fluid to push out, it can't generate much pressure on top of diastolic BP).

Also, if it helps you to think of it...your cardiac output is low, and thus the difference that your heart can produce between diastolic BP and systolic BP is decreased. Without vascular compensation, systolic falls low, only a bit above diastolic. Your body tries to maintain your overall pressure by vasoconstricting and increasing both, but cannot overcome the initial fall in systolic caused by the hypovolemia.
 
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Oh_Gee

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Remember...in diastole, the aortic valve is closed, and therefore the diastolic BP ≠ the pressure in the left ventricle. Diastolic BP is increased literally because the resistance in the arteries is increased and...that's what you're measuring.

In systole, the aortic valve is open, aortic BP = LV pressure, systolic pressure is more the result of what the heart can generate (and if it doesn't have fluid to push out, it can't generate much pressure).

Also, if it helps you to think of it...your cardiac output is low, and thus the difference that your heart can produce between diastolic BP and systolic BP is decreased. Without vascular compensation, systolic falls low, only a bit above diastolic. Your body tries to maintain your overall pressure by vasoconstricting and increasing both, but cannot overcome the initial fall in systolic caused by the hypovolemia.
so diastolic BP is basically the pressure in the peripheral circulation when the aortic valve is closed?
 
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mehc012

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so diastolic BP is basically the pressure in the peripheral circulation when the aortic valve is closed?
Yes. Diastolic BP is the lowest that the pressure in your arteries falls while the aortic valve is closed...since pressure decreases as blood distributes into the capillaries and venous system, diastolic BP is basically the aortic pressure right before your aortic valve opens back up.
 
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Kurk

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Not to sound like a dick, but this is literally EMT level stuff.
 

shisong

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in hypovolemic shock, pulse pressure narrows because of a decrease in systolic BP and an increase in diastolic BP

hypovolemic shock> decreased preload> decreased cardiac output> decreased systolic BP (i get this part)



hypovolemic shock> sympathetic reflex> increased total peripheral resistance> increased diastolic blood pressure (i don't get the bolded part)

why does Diastolic BP increase?

is it because increased TPR> increased afterload> more blood remains in left ventricle after systole than normal (which means more Diastolic BP)

another way to understand the diastolic BP is

if oyu look at B.P which is S/D. Systolic is mainyl affected by HR/heart and Diastolic is mainly affected by blood vessel resistance. so it makes sense why diastolic BP will increase with what you wrote
 
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68PGunner

in hypovolemic shock, pulse pressure narrows because of a decrease in systolic BP and an increase in diastolic BP

hypovolemic shock> decreased preload> decreased cardiac output> decreased systolic BP (i get this part)



hypovolemic shock> sympathetic reflex> increased total peripheral resistance> increased diastolic blood pressure (i don't get the bolded part)

why does Diastolic BP increase?

is it because increased TPR> increased afterload> more blood remains in left ventricle after systole than normal (which means more Diastolic BP)

Watch the sketchy autonomic sketchy video about alpha 1 alpha 2 beta 1 and beta 2 w/ QISS as the G protein pathways for each receptor if you're confused. Honestly, the whole sketchy pharm section in autonomics is super high yield for cardio once you get into drugs.
 
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