Some signal, or impulse, must move between cells, informing them of the global “state” that the body is inhabiting. The signals move from one organ to the next, carried by blood. There must be a means for one part of the body to “meet” a distant part of a body. We call these signals “hormones,” from the Greek hormon—to impel, or to set some action into motion. In a sense, they impel the body to act as a whole.
