system
Given the following post, respond as if you're commenting on Reddit:
human
How does vasoconstriction reduce blood pressure in haemostasis?

I'm a nursing student, and I'm currently studying my second physiology unit. My materials all say that when a blood vessel is damaged, vasoconstriction occurs to reduce the pressure and flow of blood, so that the platelet plug is not dislodged. This mostly makes sense to me, however it's my understanding that vasoconstriction means the same amount of blood flows through a smaller opening, thereby INCREASING blood pressure. Is there a different mechanism in place during haemostasis? Is the constriction occurring proximally to the clot, reducing the volume of blood? Is the heart output of blood changed? I can see the heart rate increasing in major injuries, thus lowering blood pressure, but what about for minor injuries?
gpt
The blood can go through more than just that blood vessel. If you have 2 vessels in parallel and one gets injured and constricts, the resistance in that vessel will increase. In that way, more blood will flow through the other vessel and less blood will flow through the injured vessel.