Define preload and afterload. What is the relationship between afterload and stroke volume?
a) Preload is the pressure in the heart at the end of diastole; afterload is the resistance the heart must overcome to eject blood. Increased afterload decreases stroke volume.
b) Preload is the resistance the heart must overcome to eject blood; afterload is the pressure in the heart at the end of diastole. Increased afterload increases stroke volume.
c) Preload is the pressure in the heart at the end of systole; afterload is the resistance the heart must overcome to fill with blood. Increased afterload decreases stroke volume.
d) Preload is the volume of blood in the ventricles at the end of systole; afterload is the volume of blood in the ventricles at the end of diastole. Increased afterload increases stroke volume.