What happens when two arteries meet in an anastomosis?

[briton]

With say arterial anastomosis (eg right and left gastroepiploic arteries) what actually happens at the region where they meet, do to the 2 arteries joining - do you just get a large build up pressure?
Is the main reason for having an arterial anastomosis so you have multiple supply to a region (so incase one artery is blocked, the distal region is still perfused)?

 

[NoTime]

FWIW
If the plumbing here was pipe then you could treat this much like two parallel resistors in an electric circuit. The pressure at the anastomosis will be higher than it would be if you clamped either right or left gastroepiploic arteries. In general there would be no "build up" of pressure. The elasticity of arteries seems unlikely to change this as the overall effect of that seems to be to damp the pressure peaks.

Since they seem to use one of these arteries for cardiac bypass it seems unlikely that the dual feed would confer a general survival benefit. My guess is that whatever guide molecule causes the arterial growth happens to diffuse to two places capable of responding to the signal at the same time.