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    Hi, I'm trying to learn the intrinsic and extrinsic mechanisms that regulate cardiac output and peripheral flow, but I'm not sure exactly what these mechanisms are... Can anyone explain it to me a little bit?

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    HI, HOPE i can provide some tips:

    A] Cardiac output:
    [I] INTRINSIC: think about it by breaking it down CO = Stroke volume X heart rate
    So changes in these two measurements will modulate cardiac output.
    a) the carotid sinus will detect drop in b.p. and increase CO via hypothalamus and sympathetic outflow + vice versa
    b) certain factors will control venous return to RV in venae cavae - CO affected via Frank-Starling Law.
    c) there are strech receptors in the myocardium that detect its state of contraction and produce control through feedback mechanisms

    [II] EXTRINSIC:
    a) when demand (for blood supply and oxygen delivery) is increased, CO is increased via the action of adrenaline (is it now called epinephrine after we succumbed to USA?!!) on beta1 receptors which will lead to a positive inotropic effect via sinoatrial node. Similarly positive chronotropic effect, - (2nd factor = heart rate)

    B] Blood flow
    [I] INTRINSIC:
    a) Various actions on smooth muscle of arterioles; NA acts on alpha1 receptors to produce vasoconstriction causing reduced blood flow - epinephrine acts on beta2 receptors (mainly in muscle) to cause vasodilatation. These lead to the predicted effects on blood flow. (the second example can be extrinsic if it is initiated by the fight, flight or fright reaction (releasing epinephrine)

    b) the various substances in the body that control blood vessel diameter (including histamine, 5-HT, leucotrienes) can modulate periphera lblood flow

    c) mechanisms specific to particular organs will control blood flow therein e.g. parasympathetic outflow to penis for erection, increased blood flow to gut after a meal.

    [II] EXTRINSIC

    Changes in environmental temp will lead to changes in skin blood flow via an effect on vessel girth - higher temp wll result in vasodilatation (causing increased blood flow to skin including to sweat glands) via hypothalamospinal tracts, to increase loss of heat by radiation as well as by evaporation of sweat.

    Hope this is a little use.
    Mukesh.
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    (Original post by macpatelgh)
    HI, HOPE i can provide some tips:

    A] Cardiac output:
    [I] INTRINSIC: think about it by breaking it down CO = Stroke volume X heart rate
    So changes in these two measurements will modulate cardiac output.
    a) the carotid sinus will detect drop in b.p. and increase CO via hypothalamus and sympathetic outflow + vice versa
    b) certain factors will control venous return to RV in venae cavae - CO affected via Frank-Starling Law.
    c) there are strech receptors in the myocardium that detect its state of contraction and produce control through feedback mechanisms

    [II] EXTRINSIC:
    a) when demand (for blood supply and oxygen delivery) is increased, CO is increased via the action of adrenaline (is it now called epinephrine after we succumbed to USA?!!) on beta1 receptors which will lead to a positive inotropic effect via sinoatrial node. Similarly positive chronotropic effect, - (2nd factor = heart rate)

    B] Blood flow
    [I] INTRINSIC:
    a) Various actions on smooth muscle of arterioles; NA acts on alpha1 receptors to produce vasoconstriction causing reduced blood flow - epinephrine acts on beta2 receptors (mainly in muscle) to cause vasodilatation. These lead to the predicted effects on blood flow. (the second example can be extrinsic if it is initiated by the fight, flight or fright reaction (releasing epinephrine)

    b) the various substances in the body that control blood vessel diameter (including histamine, 5-HT, leucotrienes) can modulate periphera lblood flow

    c) mechanisms specific to particular organs will control blood flow therein e.g. parasympathetic outflow to penis for erection, increased blood flow to gut after a meal.

    [II] EXTRINSIC

    Changes in environmental temp will lead to changes in skin blood flow via an effect on vessel girth - higher temp wll result in vasodilatation (causing increased blood flow to skin including to sweat glands) via hypothalamospinal tracts, to increase loss of heat by radiation as well as by evaporation of sweat.

    Hope this is a little use.
    Mukesh.
    Thank you!
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    you are most welcome!
 
 
 
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