In hemorrhage TPR increases (not decreases) due to reflex sympathetic nervous system.Hemorrhage would lead to decrease in blood volume and therefore venous return. Both of these would lead to hypotension (decreased TPR) and a reflex increase in HR. That's my understanding of it.
Yes you're right .. it increases TPR.In hemorrhage TPR increases (not decreases) due to reflex sympathetic nervous system.
And at one place on net i saw that increased TPR decreases heart contractility. Don't know how.
hemorrhage > decreased BP > reflex tachycardia and systemic vasoconstriction > restores BP.FA says decrease in contractility in hemorrhage (p-282 2012 edition) while kaplan says increase in contractility in hemorrhage due to reflex sympathetic (p-76 kaplan green physio). Which one is correct??
Its there. Just see in the cardiac and vascular function curve. No 3 is hemorrhage. And the reason is increase in TPR. I don't understand the mechanism.hemorrhage > decreased BP > reflex tachycardia and systemic vasoconstriction > restores BP.
So increased contractility after hemorrage makes sense to me.
my FA (2011 edition) doesnt say anything about contractility decreasing in hemorrhage.
yes, it says increased TPR, not decreased contractility.Its there. Just see in the cardiac and vascular function curve. No 3 is hemorrhage. And the reason is increase in TPR. I don't understand the mechanism.
http://www.usmle-forums.com/usmle-s...iac-output-venous-return-curves-question.htmlyes, it says increased TPR, not decreased contractility.
increased TPR is the reflex action.
baroreceptors notice the decreased BP and that causes decreased firing to the ummm medulla(?), which causes less PSNS firing and more SNS firing.
This results in an increased HR and contractility and vasoconstriction of the vessels, which means increased TPR.
look under the section named "maintenance of mean arterial pressure", and it describes this feedback loop.
however, your original comment said decreased contractility, which makes no sense and i dont know where you are seeing that.
But just now you said increased TPR, which makes perfect sense and is the way it is because of what I descrived above.
I think you are NOT talking in the same page here ,however , I really got benefit from this conversation.http://www.usmle-forums.com/usmle-s...iac-output-venous-return-curves-question.html
see in that post. both decrease in contractility and venous return occur with increased TPR.