parameters of the cardiac cycle: volume fractions, factors influencing cardiac output

Question 1

Cardiac output (CO): what is it

Answer 1

the volume of blood pumped into the circulation by the heart in one minute.(heart rate times stroke volume )

Question 2

End diastolic volume (EDV):

Answer 2

The ventricles are maximally filled at a time just before the heart contracts.

Question 3

End systolic volume (ESV):

Answer 3

When the ventricles are maximally emptied, there isstill some blood remaining in them.

Question 4

Stroke Volume (SV)= equation

Answer 4

SV)= EDV-ESV

Question 5

Cardiac Output equation

Answer 5

Cardiac Output = (EDV – ESV) x Frequency

Question 6

Measuring Cardiac Output: According to Fick’s principle: CO

Answer 6

CO: the amount of O2 taken up by the lung per minute is equal the amount taken up by the tissues, so CO = total O2 consumption (l/min) / a-v O2 difference (l/l)

Question 7

Measuring Cardiac Output: According to Stewart’s principle

Answer 7

Injecting Evans-blue i.v., sample collection & analysis, plot curve, just before recirculation do extrapolation, Area under the extrapolated curve= CO