How does donating plasma differ from donating blood?

During plasma donation, only a safe amount of blood is removed from the donor by an automated machine. The machine then separates and collects only the plasma, and the red cells are returned to the donor.

More Info: Unlike whole blood donation, you may safely donate plasma up to twice per week. Plasma is quickly replaced by your body through normal eating, drinking and daily activities. You may only donate whole blood once every 56 days.