system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do transplanted organs, connect back to the new body? Do doctors reenginner tens of millions (?) of connections back?
gpt
There really aren’t that many connections.

Take the kidneys for instance. There is the renal artery going in, the renal vein going out, and the tube for urine going to the bladder.

For the most part, that’s really it.

Sure there might be a bit of connective tissue that holds the organ in place, the body can easily grow that back though on its own, it’s pretty good at repairing itself. Arteries and veins will eventually grow into each other to make a better seal.

Similar case for the liver. One artery in, one artery out, bile duct is also connected connected, stitch those together and it should work.

Fun fact: Many organs have nerves, these are not connected during a transplant. Nerves in organs are only really needed to feel pain to tell the host that something is wrong. This includes the heart, so people with heart transplants can actually have heart attacks that they do not feel simply because the nerves are not connected.