Serum, blood and plasma

[WK]

There are loads of postings on this website about the above products.
Not knowing anything about biology or physiology, please can anyone give me a laymans answer as to the difference between these three??
Thanks in advance
WK

[HW Mueller]

The red liquid in the body is blood, when you remove the cells (erythrocytes, leukocytes, plateletts) you have serum, when you remove fibrin (the protein from which the blood clot web is made) you have plasma.

[WK]

Thanks for your perfect answer HW Mueller.
I gave blood for the first time this week - giving back some that my late mother used while in hospital. A good new year resolution to donate every 16weeks! Thought it would hurt! Nothing to it!
WK

[HW Mueller]

Darn, the answer is not perfect, indeed it´s 180° wrong. Plasma and serum should be switched. It dawned on me last night (that I switched the explanations again) after I was off the computer. One adds coagulation inhibitors (usually Ca++ binders citrate, oxalate, but probably mostly heparin) if one wants to get plasma. For serum one normally lets the blood coagulate (favorably adding materials with a surface that aid coagulation) then spins out the cells and fibrin. If one has plasma it can be converted to serum by adding Ca++ and centrifuging down the fibrin clot (Ca++ is needed in the complicated clotting cascade which converts the protein, fibrinogen, to fibrin which produces the clot fibers). This cascade requires initiation by substances set free by wounds, like the needle puncture, and ? (forgot).

[WK]

Thanks for the replies HW,
It seems like a very complicated area. I am fortunate not to work in a hospital. I'll stick to watching ER and MASH re-runs as a lay-man.
WK