Formulas

Question 1

cardiac output

Answer 1

= heart rate x stroke volume

Question 2

stroke volume

Answer 2

stroke volume = pre-load + after-load

(the amount of blood that fills the ventricle during diastole)
+
(arterial resistance that the ventricle must pump against)

Answer 3

1. Increasing the heart rate. Increasing the rate of contraction increases cardiac output up to the point at which the rate is so fast that there is inadequate time for ventricular filling.
2. Increasing the stroke volume. Up to a point, an increased force of contraction results in an increase in the amount of blood that is pumped.
3. Increasing the efficiency of the heart muscle.
4. Cardiac remodeling. The heart is composed of muscle that responds to work by increasing its size and becoming stronger. This change usually precedes the development of heart failure signs by months or years.