Regulation of Cardiac Output Flashcards
Cardiac Output (CO) =
= amount of blood pumped by each ventricle in 1 min units = ml/min
CO=
= HR (75 beats/min) X SV (70ml/beat) = 5.25
Cardiac reserve
the difference between resting and maximal CO
Heart rate is determined by rate of spontaneous depolarization of what node?
SA node
Hypocalcemia
Depresses heart
Hypercalcemia
Increases HR and contractility
Hyperkalemia
alters electrical activity, which can lead to heart block and cardiac arrest
Hypokalemia
results in feeble heartbeat, arrhythmias
afterload
Back pressure exerted by arterial blood
- is the pressure that the ventricles must overcome to force open valves and eject blood
At resting what is Aortic pressure
80mm Hg
Preload
Degree of stretch of heart muscle just before to contraction, the more the preload –> the more the stretch
eg. rubber band being stretched, depending on stretch it effects the strength of heart muscle
Contractility
stroke volume
end diastolic volume-end systolic volume
What is the most important factor in preload stretching of cardiac muscle is
Venous return
when we are resting, what is the length of the cardiac muscle?
it is shorter than the optimal length
