Hormonal cascades such as those responsible for the release of cortisol and epinephrine result in large amplifications of the initial signal and allow exquisite fine-tuning of the output of the ultimate hormone. At each level in the cascade, a small signal elicits a larger response. For example, the initial electrical signal to the hypothalamus results in the release of a few nanograms of corticotropin-releasing hormone, which elicits the release of a few micrograms of corticotropin. Corticotropin acts on the adrenal cortex to cause the release of milligrams of cortisol, for an overall amplification of at least a ___-fold.