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hi guys

can someone explain the concept of cahnges in arteriole resistence during exercise its blood confusing

arteriloes dilate to increase oxygen supply but would that not decrease pressure in the system??
 

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YOU can remember this simple formula,
MAP = CO multiplied by TPR
where, MAP is mean arterial Pressure, Co is cardiac output, TPR is total peripheral resistence
so CO increases in exercising muscle, which may also inc the MAP but MAP is not inc cuz TPR is decreased, so MAP remains same!
 

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Excercise and MAP

Adequate amounts of oxygen cannot be delivered immediately after exercise has begun. Consequently muscle stores of creatine phosphate, myoglobin oxygen and ATPase are used until a sufficient amount of oxygen can be delivered to tissue.
In excercise there is a decrease in vascular resistance(decreased TPR) because of arteriole dilation, there is an increase in capillary filtration rate and an increase in lymph flow.
The pressure in the system is not decreased because Cardiac output is increased (heart rate, stroke volume).
So as stated before; MAP=COxTPR
It is all a matter of compensation. The cardiac and vascular function curve demonstrate the increased in cardiac output following a decreased of TPR as in the case of excercise.
http://wapedia.mobi/thumb/cc86505/e...g,gif&ctf=0?format=jpg,png,gif&loadexternal=1
 

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Mean Arterial Pressure: (systolic - diastolic )is not changed as much as expected despite the increase in cardiac output to 20 L/min! why is that? the sympathetic system is activated by exercise and there is vascular constriction in all peripheral organs (even kidneys) except muscle.Muscle vessels dilate due to release of local vasodialtors: lactic acid, ATP,Adenosine,Pottassium,and CO2. Muscles receive 85% of CO! So there is an adaptive decrease in svr keeping rise in BP during exercise to be not too much.
 
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