Regulation of Cardiac Output Flashcards
What formally defines arterial pressure?
The product of cardiac output and arterial resistance
What is teh Cardiovascular equivalent of Ohms Law?
Q (flow)= P (Pressure difference between two points) / R (resistance)
Define the cardiac function curve
It is ventricular output as a function of atrial pressure
Define the vascular function curve
Venous return as a function of atrial pressure
Atrial pressure, in the cardiac function graph, is really a stand-in for what?
Diastolic Pressure/ Ventricular Pressure.
Really equals preload pretty much.
Increased atrial pressure does what to heart rate and how?
Increases heart rate by in increasing pacemaker activity. This causes increased cardiac output
Increased atrial pressure has what effect on ventricular stretch and how?
Increased ventricular stretch due to increased ventricular fluid volume. This leads to increased ventricular stroke volume.
Four factors that regulate the cardiac function curve?
Sympathetic and parasympathetic activity, Intrinsic ventricular effectiveness,
afterload,
intrapleural thoracic pressure.
What is the effect of a more negative intrapleural pressure on ventricular output?
It increases it. Why?
B/C ventricular stretch is determined by end diastolic pressure (pressure inside ventricles after complete fill) and intrapleural pressure.. When intrapleural pressure decreases, it leads to more stretch and greater stroke volume.
Frank Starling mechanism?
relationship between ventricular stretch and output
Increase in atrial pressure does what to venous return?
Decreases it
What is the x axis intercept on the vascular function curve?>
Mean systemic filing pressure
Define filling pressure?
Pressure needed to fill the blood vessels beyond their intrinsic volume. Basically how much pressure it takes to stretch them. The blood volume and the size of the veins determines it. Filling pressure and resistance then determines vascular function curve.
What sets the slope of the venous function curve?
Things that regulate resistance to venous return
Which has the greatest effect on venous return? Filling pressure change or TPR change
Filling pressure change
