Woodward questions throughout lecture

Based on your knowledge of the heart, can you explain why cardiac output during both exercise and the paced heart deviates from the expected line during increased heart rate?

Because in a paced heart, we increase the frequency of systole to increase the heart rate, which will decrease the amount of time in diastole and since SV= EDV - ESV, if we decrease EDV that decreases SV which decreases CO, which is why the paced heart’s slope is lower.

In a healthy heart during exercise, the heart rate increases because we increase the frequency of the cardiac cycle (both systole and diastole) so the amount of time in diastole also increases which will increase SV, thus increasing CO, which is why the slope is higher.

Which of the following could increase cardiac output (in a healthy heart)?

Increasing preload

Based on your understanding of heart sounds and blood flow through the heart, where on the phonogram let you hear a murmur from mitral/bicuspid valve incompetence? What sound would that be? What about PDA?

It would be a systolic murmur and you’d hear a Lub-SHH-Dub

PDA is continuous so it would always be there

What happens to increase venous pressure and venous return?

80 bpm

Draw a contractile cell action potential versus a autorhythmic cell action potential