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Cardiac Output- Volume of blood pumped by each ventricle in 1 minute
CO =…
Cardiac Output- Volume of blood pumped by each ventricle in 1 minute
CO = heart rate (HR) × stroke volume (SV)
Increasing either HR or SV, increases cardiac output
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Stroke volume (SV) = volume of blood pumped out by one ventricle each beat (70 ml/beat)
SV=EDV-ESV
Increase in SV, increase CO
End diastolic volume (EDV)(preload)- amount of blood collected in a ventricle during diastole
Increase in EDV, increases SV
Venous return- amount of blood returning to the heart Increase in venous return, increases EDV
Ventricular filling time- increase in ventricular filling time (due to decreased heart rate), increases venous return
Exercise (by increased sympathetic activity, increased skeletal muscle and respiratory pumps) - increases venous return
End systolic volume (ESV)- amount of blood remaining in a ventricle after contraction
Decrease in ESV, increases SV
Contractility- Contractile strength of the cardiac muscle tissue. Increase in contractility, decreases ESV
Positive inotropic agents - causes increased contractility. ex- Bloodborne epinephrine, thyroxine, excess Ca2+
Negative inotropic agents - decrease contractility. ex. - acidosis, increased extracellular K+, calcium channel blockers
Afterload- back pressure exerted by arterial blood. Hypertension causes increased after load which causes increased ESV
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