52.3 Integrated Control of Cardiac Output Flashcards
How is cardiac output linked to central venous pressure? (2 linked ways)
It both determines CVP and is affected itself by CVP
What is central venous pressure?
Blood pressure in vena cava
(next to right atrium)
Explain why increased CVP results in increased cardiac output
Increased CVP = increased preload = increased stroke volume (and increased CO)
Guyton’s curves (venous return curves) show the relationship between…
right atrial pressure and venous return
(Guyton’s curve) What is the effect of increasing blood volume?
Shifts curve to the right
so higher RAP required for same venous return/cardiac output
(Guyton’s curve) What is the effect of decreasing blood volume?
Shifts curve to the left
Guyton’s curve) What is the effect of arteriolar vasodilation?
Steepens the curve, but same x-intercept
(Guyton’s curve) What is the effect of arteriolar vasoconstriction?
Flattens the curve, but same x-intercept
What is marked by the x-intercept on Guyton’s curves?
Mean systemic filling pressure
Why does arteriolar tone have little effect on mean systemic filling pressure (MSFP) but does have an effect on venous return?
Little effect on MSFP bc arteriolar volume is only a minor fraction of the blood volume
Effect on venous return bc it can affect CVP –> affects right atrial pressure –> affects venous return
What is the Frank-Starling law?
Relationship between end-diastolic volume and stroke volume
What does the Frank-Starling mechanism state?
As the myocardium stretches to a greater volume in diastole the sarcomeres align closer → greater contractile force and greater stroke volume.
Starling’s curve is also known as the…
Cardiac function curve
Guyton’s curve is also known as the…
Vascular function curve
What is compliance?
The ease with which a change in pressure induces a change in volume in the vessel/ index of elasticity
