Eli5: How does Saline Solution work within the blood stream?

Question

Fellows,

I’m reading about donating blood, and they said that in large volume plasma donation, a replacement of saline is added to your blood stream to account for the large volume taken. I’m just wondering how it’s okay to just replace blood with Saline

In: 13

Answer 1

Saline is just slightly salty water. They inject that into donors to prevent a drop in blood pressure. The stuff that’s in the donor’s plasma that the recipient needs (platelets, for example) will be replenished by the donor’s body on its own.