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Basic PHYS201::L06 Cardiac output and what sets it Cardiac output: through which two variables must any change in cardiac output act? Heart rate or stroke volume
There is no third way to change cardiac output. L06 @ 00:05:52, slide 2 "anything that changes cardiac output has to do it either by changing heart rate or by changing stroke volume" PHYS201::L06 cardiac-output-stroke-volume-ejection-fraction
Cloze PHYS201::L06 Cardiac output and what sets it Stroke volume: set by three things, namely preload, afterload and {{c1::contractility}}. The lecturer says you need to know these three cold. L06 @ 00:06:23, slide 3 "you need to know these three cold. Preload, afterload, and contractility" PHYS201::L06 cardiac-output-stroke-volume-ejection-fraction
Basic PHYS201::L06 Cardiac output and what sets it Frank-Starling law: what happens to stroke volume when end-diastolic volume increases? Stroke volume increases
Within limits, the heart pumps out whatever is returned. L06 @ 00:08:31, slide 4 "If you increase the end-diastolic volume, the ventricle responds by ejecting a bigger stroke volume" PHYS201::L06 preload-and-the-frank-starling-law
Basic PHYS201::L06 Cardiac output and what sets it Frank-Starling mechanism: what changes about calcium in the filaments, given that the amount of calcium stays the same? The filaments' sensitivity to calcium
This is what separates the mechanism from contractility. L06 @ 00:12:28, slide 5 "in the Frank Sterling [?Frank-Starling] mechanism the amount of calcium does not change" PHYS201::L06 preload-and-the-frank-starling-law
Basic PHYS201::L06 Cardiac output and what sets it Afterload: what happens to stroke volume when afterload rises with preload and contractility unchanged? Stroke volume falls
L06 @ 00:14:59, slide 6 "If afterload goes up, and preload and contractility stay the same, stroke volume goes down." PHYS201::L06 afterload-laplaces-law-and-contractility
Basic PHYS201::L06 Cardiac output and what sets it Frank-Starling curve: how does more contractility move the ventricle, compared with more preload? Onto a higher curve
More preload moves the ventricle along the same curve. The higher curve is shifted upwards and to the left. L06 @ 00:20:20, slide 7 "more preload moves you along the same curve; more contractility moves you onto a higher curve" PHYS201::L06 afterload-laplaces-law-and-contractility
Basic PHYS201::L06 Cardiac output and what sets it Pressure-volume loop: which way does the bottom right corner move when preload increases? To the right
The ventricle fills more, so the loop widens and stroke volume rises. L06 @ 00:23:35, slide 8 "the bottom right corner moves to the right, the loop gets wider, stroke volume up" PHYS201::L06 pressure-volume-loop-exercise-and-heart-failure
Basic PHYS201::L06 Cardiac output and what sets it Pressure-volume loop: how does the loop's shape change when afterload increases? Taller and narrower
The aortic valve opens later, at a higher pressure. End-systolic volume is higher and stroke volume is lower. L06 @ 00:23:43, slide 8 "the aortic valve opens later, at a higher pressure, so the loop gets taller and narrower" PHYS201::L06 pressure-volume-loop-exercise-and-heart-failure
Basic PHYS201::L06 Cardiac output and what sets it Pressure-volume loop: what happens to end-systolic volume when contractility increases? End-systolic volume falls
The ventricle empties further, so the left side of the loop moves leftwards, the loop widens and stroke volume rises. L06 @ 00:23:58, slide 8 "the left side of the loop moves to the left, end-systolic volume is lower, the loop is wider, stroke volume up" PHYS201::L06 pressure-volume-loop-exercise-and-heart-failure