Platelets, also called thrombocytes (thromb- + -cyte, blood clot cell), are a component of blood whose function (along with the coagulation factors) is to stop bleeding by clumping and clotting blood vessel injuries.
Milk of the poppy is essentially the Westeros version of morphine. Maesters make it from crushed poppy flowers, and morphine and other opiate-based drugs are made from poppy plants. Indeed, the books' descriptions strongly suggest that the poppy is intended to be the real-world opium poppy (Papaver somniferum).
Poppy seeds contain opiates. Just a heads up on the opiate content of poppy seeds for those of us whose baked goods might be eaten by someone in the military and other services which do random urine tests.http://snopes.com/medical/drugs/poppyseed.asp.hich was rather silly, since normal poppies while they do contain the opiate etc, it takes so many to make even a small amount of codiene base, the opium poppies have more sap, and if you've ever seen an opium poppy field its acres and acres to make the rather small amount of base they truly get from a farm.