Healing Seringe...

In games like Rainbow Six Vegas, Battlefield: Bad Company, Far Cry 2 (this last one's a bit different), you use seringes to heal. In the case of R6V2, to heal a downed teamate.

Do military use seringes like that in some situations? Does anybody know what's inside, adrenaline perhaps? What's the name of that?

For the most part, it is just a game thing. Just as in the way of eating a turkey or steak that refills your health.

They have syringes, but they don't do the same thing. Maybe adrenaline to keep them going till they can get real medical help, but that is about it.