Sera Is the Latin Plural of Serum
Sera are blood serums. The word names the fluid left after blood clots.
Sera is the plural of *serum*, the clear yellowish fluid that separates from blood when it clots. Serum is not the same as plasma, though the two are often confused: plasma is the liquid part of blood including clotting factors, while serum is what remains once those factors have been used up in forming a clot. Blood tests usually measure serum; transfusions often use plasma. Latin *serum* meant whey, the watery part left when milk curdles — exactly the same image.
- Blood serums. *Immune sera.*
- Serum — the singular. *Serum.*
- Plasma — a different thing. *Plasma.*
- Antiserum. *An antiserum.*
- Latin — *serum*, whey. *The root.*
Word forms
| Form | Word | Example |
|---|---|---|
| Singular | serum | Serum. |
| Plural | sera | Sera. |
| Variant plural | serums | Serums. |
| Related | plasma | Plasma. |
| Latin | serum | Whey. |
- The sera were tested.Plural.
- Serum is not plasma.Distinction.
- Serum meant whey.Etymology.
What blood separates into
- Red cells — carry oxygen, about 45 percent by volume
- White cells and platelets — a thin layer between
- Plasma — the liquid, including clotting factors
- Serum — plasma after clotting has removed those factors
- A centrifuge separates the layers in minutes
Latin *serum*, whey or watery fluid, plural *sera*.
What is the difference between serum and plasma?
Plasma is the liquid part of blood including clotting factors; serum is what remains after clotting has consumed them.
Why does serum mean whey in Latin?
Because the watery fluid left when milk curdles looks exactly like the fluid left when blood clots.