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Capillary and Venous Blood Pressure (Nursing)

by Jasmine Clark

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    00:01 So our capillary blood pressure is going to be much lower than arterial blood pressure.

    00:07 It's going to range from 35 mm Hg at the beginning of the capillary bed to 17 mm Hg at the end of the capillary bed.

    00:18 Below capillary pressure is desirable, because if the pressure was too high, it would rupture the very fragile and thin-walled capillaries.

    00:29 Most of our capillaries are also very permeable, so a low pressure would force the filtrate in the capillary to leak out into our interstitial spaces.

    00:40 So now moving on to our veins.

    00:43 The venous blood pressure is going to change very little during the cardiac cycle.

    00:49 There is a small pressure gradient of only about 15 mm Hg.

    00:54 So, if a vein is cut, the low pressure of the venous system is going to cause the blood to flow out nice and smoothly.

    01:03 This is in contrast when an artery is cut.

    01:06 In this case, blood is going to spurt out because the artery system is a much higher pressure system.

    01:14 The low pressure in our veins is due to the cumulative effects of peripheral resistance, The energy of the blood pressure is lost as heat during each circuit.

    01:25 And the low pressure of the venous side requires adaptations in order to help the venous blood return to the heart.

    01:35 The factors that we use to aid venous return include the muscular pump, where the contraction of our skeletal muscles milk the blood back toward the heart.

    01:47 At the same time, valves present within our veins are going to prevent backflow of the blood so that is constantly moving up and not going backwards.

    01:58 We also have a respiratory pump.

    02:01 Where pressure changes during the breathing, move our blood toward the heart by squeezing our abdominal veins and our thoracic veins as they expand.

    02:12 Finally, we have sympathetic vinoconstriction, we're under sympathetic control, the smooth muscles are going to constrict and push blood back toward the heart.

    02:25 So depicted is the milking action of the skeletal muscles that's going to propel the venous blood from the lower extremities toward the heart.


    About the Lecture

    The lecture Capillary and Venous Blood Pressure (Nursing) by Jasmine Clark is from the course Cardiovascular System: Blood Vessels – Physiology (Nursing).


    Included Quiz Questions

    1. Muscular pump
    2. Respiratory pump
    3. Sympathetic venoconstriction
    4. Filtration
    5. Reabsorption

    Author of lecture Capillary and Venous Blood Pressure (Nursing)

     Jasmine Clark

    Jasmine Clark


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