Blood Pressure is increased when:

[RP29]

Blood pressure is increased when: sympathetic activation decreases the diameter of arterioles systemically.


Can someone help me examine this problem/answer? I thought that sympathetic activation increases the diameter of arterioles. Does the part about 'systemically' mean the digestive system/skin?

Thank You!

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[zanbeo]

hey,
it makes more sense if u look at the equation of flow rate F=P/R. sympathetic causes vasoconstriction, which decreases the diameter of the arteriole, thus increase the resistance in arteriole. the formula for resistance is as followed: R=8Ln/3.14r^4. so small change in radius will cause resistance to increase greatly.
if resistance increase n pressure stays the same, it will decrease blood flow. however, the body always wants to maintain balance, so if resistance increase, pressure will have to increase as well to keep the blood flow the same.
when u increase the diameter of the arteriole, the resistance decrease, which will result in a decrease in pressure.

 

[npparikh90]

Blood pressure is increased when: sympathetic activation decreases the diameter of arterioles systemically.


Can someone help me examine this problem/answer? I thought that sympathetic activation increases the diameter of arterioles. Does the part about 'systemically' mean the digestive system/skin?

Thank You!

adding to the response from the person above me systemic just means throughout the body so during sympathetic activation there is a "systemic" Vasoconstriction and vasoconstriction or reducing the diameter always increases the pressure if you look at the formula mentioned above or even if you look at the formula of pressurepressure = force/area so when you decrease the diameter area also decreases and hence pressure increases or think that same amount of liquid bouncing more often against the wall of the arteries (more resistance) and hence more pressure.

Important thing to remember is two things that affect blood pressure is cardiac output and resistance