Stroke Volume

	Stoke volume is the amound of blood that is pumped out of the heart
at every beat.  There are two ways to find Stroke volume.  If the cardiac
output and the heart is known, the stroke volume can be found using this
equation:
	stroke volume = cardiac output / heart rate.

	Another way to determine the Stroke volume is to subtrack the end 
systolic volume from the end diastolic volume.  Thus you take the volume at the
end of relaxation, and subtract the amount of blood that is left in the heart 
after contraction.

	Both end diastolic volume and end systolic volume effect the stroke 
volume.  The can be effected by the amount of venous flow into the heart, the
heart rate, total peripheral resistance, starlings law, and ventrical 
contractility.

Sample Problems:

Question #1:
	If a heart fills up to 200ml of blood before contraction, and leaves 
	50ml in the heart after contraction, what is the stroke volume?  If 
	heart rate was 80 beats per minute, what would the cardiac output be?

Question #2:
	if the total peripheral resistance goes up, what is likely to happen to
	the stroke volume?

Answers:

Answer #1:
	a) 150ml/beat
	b) 12 L/minute

Answer #2:
	The stroke volume will go down.

For more information on this topic, please refer to Berne & Levy , 66, 83

Also, check out the following links that may be helpful:

• cardiac output and venous return
• or NASA, my employer, might help you!
• And, as always, if you have questions, or if you can suggest a helpful link, please e-mail me.

No!
Please don't make me go to any of those pages!
I want to go somewhere completely different!

This page was written by Matt Reaves , a student in this course.

BME 403 Pages maintained by the T.A., Douglas Miles.