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Cardiac Output, Flow, Pressure and Resistance Theory – Cardiac Mechanics

by Thad Wilson, PhD
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    Cardiac mechanics is the next topic. Here, we need to talk a lot about how much cardiac output we have. What is cardiac output? It’s the volume of blood ejected by the heart per minute. How do we determine what someone's cardiac output is? You take the stroke volume, which is the bolus of blood ejected per stroke times the heart rate. The reason why we go through this process is because we have two main variables to alter. Chronotropy, or heart rate, governs the pump frequency. Stroke volume governs how much push out we have per beat of the heart. There are a number of factors that govern the control of both stroke volume and heart rate. Some of them are going to be very similar between the two. Other ones have some inherent differences. Just to go through a few of the stroke volume ones. Autonomic nervous system, such as increases in norepinephrine secretion, that will increase contractility, which causes a greater stroke volume. Hormones, such as epinephrine, also can feed into that beta-1 adrenergic response and increase the bolus of blood ejected per stroke. Interestingly, there are some intrinsic factors, besides nerves and hormones, that can also increase stroke volume. And that is the heart has a very unique principle, in which the more it is stretched, the harder it contracts and we’ll go through that in more detail here in subsequent slides. Heart rate is governed by both autonomic nerves and hormones, but doesn't have some of those intrinsic factors that stroke volume has. So, what constitutes a stroke volume? How do you know how much bolus of blood is ejected per stroke? Well, for this, you need to know what the end-diastolic volume is, Well, for this, you need to know what the end-diastolic volume...

    About the Lecture

    The lecture Cardiac Output, Flow, Pressure and Resistance Theory – Cardiac Mechanics by Thad Wilson, PhD is from the course Cardiac Physiology.


    Included Quiz Questions

    1. Preload
    2. Afterload
    3. Stroke volume
    4. Inotropy
    5. Dromotropy
    1. Stroke volume × Heart rate
    2. End systolic volume ÷ Heart rate
    3. End diastolic volume × Heart rate
    4. End diastolic volume – Heart rate
    5. End diastolic volume – End systolic volume

    Author of lecture Cardiac Output, Flow, Pressure and Resistance Theory – Cardiac Mechanics

     Thad Wilson, PhD

    Thad Wilson, PhD


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