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| Front | Back |
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Equation for cardiac output (___ x ___ =CO)
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Heart rate (HR) x stroke volume (SV) = CO
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Equation for mean arterial pressure Part
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Cardiac output (CO) x peripheral resistance (R) = Part
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Properties of a healthy heart
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CO = VR
cardiac output = venous return out = in |
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Briefly describe the cardiac cycle
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 -atrial contraction -increased arterial pressure -ventricle filling -EDV (end diastolic volume) -ventricular contraction -increased ventricular pressure -when Pvent>Patr, A-V valves close (1st heart sound) -isovolumetric ventricular contraction -ejection (ventricular blood volume decreases) -aortic valve and pulmonic valves close when active contraction ends and enough blood is pumped out through the aorta (2nd heart sound) -isovolumetric relaxation (R and L ventricles, R at lower pressures) |
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What is responsible for the first heart sound?
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Closing of A-V valves
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What is responsible for the 2nd heart sound?
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Closing of aortic and pulmonic valves
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When Pvent< Patr
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A-V valves are open and ventricles are filling with blood from pulmonary veins
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Stroke volume = change in volume =
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EDV - ESV
end diastolic - end systolic volume |
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EDV can be estimated by measuring which two variables?
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End diastolic pressure (preload)
or atrial pressure |
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How does the heart increase SV?
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Size of heart increases, EDV increases
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T or F
The heart can develop greater ventricular pressure when it is larger |
T
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Does CO vary much with changes in Part?
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No, unless you are at the extremes of Part (very low or very high)
 |
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How does increasing the heart rate affect contractility of the heart?
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Increasing the heart rate leads to increase in calcium influx and increase in calcium release from SR with each beat
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What are 2 factors that can increase contractility of the heart?
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-increasing catecholamine levels in the blood
-increasing sympathetic ANS stim |
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What effect does increasing cholinergic (parasympathetic) stim have on the heart?
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Decreases contractility (opposite effect of sympathetic ANS stim)
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