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human
ELI5: How does suturing veins prevent blood from leaking out?

As the title stated, how does suturing veins prevent blood from leaking out? Wouldn't the gaps between the sutures and holes from sutures cause continuous or more bleeding?
gpt
Blood has its own built in plugging mechanism.

They’re called platelets, they constantly circle around the blood stream, and when the interact with a cut/hole/damage to the blood vessel they start to clump/tangle up with other platelets, causing a clog that seals the damage and stops the bleeding.

So when you suture a vessel shut, you’re taking a really big hole/cut and making it a smaller hole/cut by pulling the edges together. 

This help slow the flow a blood by making the hole/cut smaller.

Then, the platelets in the blood naturally finish up the job by plugging any of the small holes/cuts/opening that remain.