Lectures

Coronary Circulation – Special Circulations

by Thad Wilson, PhD
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    As we move on to the coronary circulation, here we need to think about relaxing and contraction of muscles. So the heart is a muscle, it has myocytes. So where are we going to get blood flow when a muscle contracts or relaxes? This is a great example of how this process works. If we look at the pressure in the aorta, which is blood pressure that's going into the systemic circulation. Systole is the part where you have the highest blood pressure. You notice though when it has the highest blood pressure, blood flow which is the second row here, is the lowest. So when the heart is contracting, it is not getting blood flow. Only when the heart relaxes does it get blood flow. So this sets up a very unique process where during the contraction of the heart, the heart receives very little of the blood flow it's delivering to the rest of the body. Only when it relaxes does it obtain the flow necessary for it to exchange nutrients. This process becomes important especially when you think about how much work the heart has to do. It's beating 60 to 100 times every minute every hour of every day. Every time it beats, it loses blood flow during the contraction phase. How this process works is that any time there is squeezing of the skeletal muscle, it pushes together some of the very small blood vessels. Therefore, only during the relaxation phase do those blood vessels open up and engorge the particular coronary myocytes with blood and this increase in blood flow can be quite dramatic as we saw in the previous graph. What controls the blood flow besides contraction? For this, you need to think about other muscles and how the regular circulation is...

    About the Lecture

    The lecture Coronary Circulation – Special Circulations by Thad Wilson, PhD is from the course Vascular Physiology.


    Included Quiz Questions

    1. Functional sympatholysis
    2. Forced vasodilation
    3. Forced vasoconstriction
    4. Reactive hyperemia

    Author of lecture Coronary Circulation – Special Circulations

     Thad Wilson, PhD

    Thad Wilson, PhD


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