Define Cardiac Output (CO).
Amount pf blood pumped out by each ventricle in 1 minute
Write the equation for CO.
Cardiac output(CO)= Stroke volume(SV)x Heart rate(HR)
Define stroke volume (SV).
The volume of blood pumped out by one ventricle with each beat.
Write the equation for SV.
Stroke volume(SV)= End diastolic volume(EDV)- End systolic volume(ESV)
Write the normal values (include correct units) for the following:
a. HR (heart rate)=_____________________________
b. SV (stroke volume)=__________________________
c. EDV (end diastolic volume)=__________________
d. ESV (end systolic volume)=___________________
a. 75 bpm
b. 70 ml
c. 120 ml
d. 50 ml
Given the values for HR and SV, calculate cardiac output:
CO= SV x HR
CO= 70 x 75
Explain how the following factors affect HR, SV, and CO by placing arrows (up-arrow, down-arrow, or <--> for no change) under them.
a. Increased SNS
b. Increased Venous return
d. Increased Calcium
e. Decreased HR
a. up-arrow HR, up-arrow SV, up-arrow CO
b. down-arrow HR, up-arrow SV, up-arrow CO
c. up-arrow HR, up-arrow SV, up-arrow CO
d. up-arrow HR, up-arrow SV, up-arrow CO
e. down-arrow HR, up-arrow SV, <--> CO
Why would stroke volume increase with an increase in the sympathetic nervous system or an increase in calcium?
Activation of the sympathetic nervous system, or and increase in calcium, will stimulate beta 1 receptors in the heart increasing cardiac muscle contraction, and increasing the stroke volume.
Why would stroke volume increase when heart rate slows down?
Beacuse it increases EDV and consequently the stroke volume and contraction force, a slow heart rate allows more time for ventricular filling.