Question

what role do blood banks play in the human body

Answer 1

by storing blood for when there is less blood

Answer 2

A blood bank is a cache or bank of blood or blood components, gathered as a result ofblood donationor collection, stored and preserved for later use inblood transfusion. The term "blood bank" typically refers to a division of a hospital where the storage of blood product occurs and where proper testing is performed (to reduce the risk of transfusion related adverse events). However, it sometimes refers to a collection center, and indeed some hospitals also perform collection.