Obviously, muscular effort involved in touching is meager, and so is brain blood perfusion. Yet it may be raised when walking or by any other exercise. Process interleaving In order to supply the brain with necessary nutrients, the liver has to produce them, and its metabolism rises slightly. Other organs are also involved. The kidney adapts its urine production.
Endocrine glands produce more hormones. . .
Touching your nose triggers myriad processes in the body, mobilized to support your wish. This example illustrates another important phenomenon, process interleaving. Since all processes in the body interact, they boost each other, and if one fails, others assist it. It does, yet the effect is small. Other ways may be more effective.