Naked Science Forum

Life Sciences => Physiology & Medicine => Topic started by: Chivalrous on 06/04/2015 18:51:33

Title: Topic Deletion Request
Post by: Chivalrous on 06/04/2015 18:51:33

I'd like to delete that topic as I haven't received more replies concerning my questions.
But Dr. Chris,
Thanks a lot for your reply, I really appreciate it. You have clarified some points for me.  [:)]

Title: How is cardiac contractility affected by pre-load (force-velocity relationship)?
Post by: chris on 07/04/2015 13:13:56

The force increases because, as the graph states, a positive inotrope is used, which increases muscle contracility and therefore force delivered for the same preload.

Tachycardia is just a change in rate, without necessarily a change in contracility. At progressively higher rates there is insufficient time for complete filling. Noradrenaline is positively inotropic and positively chronotropic, so it increases contracility, which is why the curve is not the same as for tachycardia alone.