system
Given the following post, respond as if you're commenting on Reddit:
human
How do things like arteries stay “watertight” after being stitched together in an operation?

When something like an artery is repaired and stitched together how does it become sealed? Is it just regular clotting the way blood repairs skin cuts etc or something else?
gpt
It's mostly just by placing very small sutures usually 6-0 or 7-0 prolene very close together with the help of magnifying lenses.

The way that they are sewn together is also maybe not immediately intuitive, but they are not just sewn together end to end, but the edges are trimmed at angles to form much larger ovals that are sewn together and distribute the pressure along the repair over a larger area and so that they can overlap more and gives more room to place more sutures.

When tying the final knot it is also very important to get the tension in the suture just right so that it is under enough tension to hold everything together, but not so tight that you rip the suture through tissue or have everything bunch up into a ball.