Kenneth S. answered 07/22/19
Professor's Assistant with a Graduate-Level Biology Background
Hello Joel F.!
In response to your question, inflammation alone would not cause a decrease in blood flow from a wound. Inflammation occurs as an immune response to foreign substances (like bacteria and other pathogens). It actually increases blood flow at that site by dilating blood vessels and allows your white blood cells (hanging out in your circulatory system) to easily leave your vessels at the infected site like a car taking an off ramp from a highway.
Decreasing blood loss from a wound is typically the responsibility of platelets (in your blood) and molecules called fibrin. The process of clotting blood to patch up a wound is started by vessel damage. This can be internal (bruises) or external (cuts/scrapes) but either way, a vessel is damaged to the point that molecules called collagen falls into it. Collagen is very common in our tissues but never seen in our blood vessels. When this happens, our body is being told something is wrong. This kicks off the clotting process.
BOTH blood clotting and inflammation tend to be paired together because events that cut your skin and bring in foreign pathogens ALSO tend to damage blood vessels and start off the clotting process.
I hope this helped clear things up!
-Ken