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Urgent!! Help! Biology concept about arteries

In my lecture notes on the "effects of arterial radius on the resistance of ccardiovascular system"
There are two point,
(1)vasoconstriction -->radius ofarteries decreases -->resistance increases

(2)since the overall resistance of systemic circuit is higher than that of pulmonary circuit, to maintain the same flow rate of blood , less pressure change is required.

I dont understand why point 2 is related to "effects of arterial radius on the resistance of ccardiovascular system", could someone please explain it to me ? @@

Thank you very much ! I had a final tmr @@
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Reply 1

Mimir

A final what?

The radius of the lumen in the arteries, which can alter, is a contributing factor to the resistance the blood faces as it flows through the systemic circuit. Imagine blowing a set volume of water through two different straws. A really thin one would require more force to blow the same volume through compared to one as wide as a McDonald's straw, which lets more liquid pass through per second with less force required to move it.

Point two probably refers to the fact that radius of the arterial lumen can be used to change systemic blood pressure according to demand or as a response to other physiological changes?

(Trying to make my answer as simple as possible, not sure what year you're in at Uni)