Endocrine System:The endocrine system is a collection of glands that produce and secrete hormones directly into the bloodstream to regulate essential bodily functions.
Signal Transduction: The process by which a cell converts one kind of signal or stimulus into another, relaying the message through a series of molecular events.
Second Messengers: Intracellular signaling molecules that are produced in response to the binding of a hormone to its receptor, amplifying and propagating the hormonal signal within the cell.