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Cardiac Output, Physiology of the cardiovascular systemic
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Greta Donisi Pecchiari Lesson 11 - 23/03/2015
Mechanical coupling between the heart and the vessels
this man here is Guyton, the author of the book.
(slide 1, above) What you see here is an electrical circuit consis
distance between the total PV curve and the x axis in the rst graph drawn). the two structures are mechanically in parallel and therefore the pressure dierence between the inside and the outside is given by the sum of the pressure dierence across each individual part.
This occurs in normal condi
(slide 7, above) Consider a normal cardiovascular system (panel A); this is however a model, the elements of these model are made by: the pump including not only the two parts of the heart but also the lungs, so you can imagine this is a pump- oxygenator and its equivalent to the heart-lung prepara
Q: in the model in which we have also the resistances, why Rv is only due to big veins?
A: because you can if you want think about the resistance of the small veins but the fact is that Rv occurs aTer the compliance soma least in the model should be aTer the capacitance vessel. Guy-ton made several of these models with dierent subdivisions of the venous compartment of the arterial compartment and so on and each of this compartment was represented by a compliance and a resistance. I choose this one because it is rather simple and gives you an idea of what hap-pens when you change arteriolar resistances and when you compress the veins.
You can imagine that if the venules and small veins were the big capacitance vessels you could stretch the model and say that Rv is the resistance aTer these vessels.
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