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 Vaso vs. Veno constriction and dilation  



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Author4 Posts
  #1

Vasoconstriction increases TPR (any effect on CO)?
Vasodilation decreases TPR (any effect on CO)?

Venoconstriction increases CO -because increase venous return (and no effect on TPR)
Venodilation decreases CO -because pooling of blood in veins (and no effect on TPR)










  #2

first of all you have to remember that the entire systemic circut is connected in series .the flow in any part is equal to another part.

secondly, if u add a resistence to a system connected in series u wiil an equal decrease in flow in all parts of that system.SO YES INCREASING TPR WILL DECREASE THE CARDIAC OUTPUT INITIALLY.

BUT PRESSURE WILL EVENTUALLY INCREASE TO OVERCOME THE RESISTANCE AND RESUME FLOW.

(THIS IS THAUGHT TO BE THE IDIOPATHY OF ESSENTIAL HYPERTENSION.



  #3

I MEANT THE PATHOGENESIS OF ESSENTIAL HYPERTENSION.


  #4

IN TERMS OF OTHER CHANGES LIKE:CHANGE IN TPR AFTER CHANGE IN CO DUE TO VENO DILITATION,HERE YOU SHOULD ALWAYS REMEBER THAT

1:MAP=CO *TPR

SO A CHANGE IN ONE WILL CHANGE THE MAP WHICH IS DETECTED BY CAROTID SINUS THAT,IN TURN, TENDS TO CREATE CHANGES IN CO AND TPR IN AN ATTEMPT TO RETURN BLOOD PRESSURE BACK TO ITS NORMAL SET INDEX








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