For those who have a weak stomach, don’t read / look at this. I donated plasma, which I often do Saturdays, but I noticed this time at the end of the donation a little plastic filter-looking thing. I asked the nurse (or technician), “What the heck is that?” “It’s a blood filter,” she said. It apparently collects dead blood cells!
First, the blood is taken out through the arm. It then gets spun in a centrifuge to remove plasma. After, it gets put back into the body through the same tube. While adding the blood (minus a lot of the plasma) back in, it filters it.
So it’s basically cleaner when they put it back in than when they remove it. Funny, I never noticed this before. Cool. But gross.