A hormone is a product of an endocrine gland that is released into the blood. Hormones regulate development and activity in target tissues somewhere else at a distance in the body. Steroid hormones include cortisol, estrogen, and testosterone. Non-steroid hormones include choleckystokinin, epinephrine, dopamine, insulin, norepinephrine, serotonin, and vasopressin. Steroid hormones, like estrogen, directly affect gene expression in their target cells. These hormones are lipid soluble and can diffuse directly through the the plasma membrane …showed first 75 words of 244 total…

…showed last 75 words of 244 total…activates the next enzyme in the series. These enzyme cascades amplify the effects of hormone molecules on target cell metabolism. When the blood sugar level lowers, insulin is released. The same basic mechanisms are used in many diffferent hormone and target cell combinations, but the response is specific. Cells can only interact with only the hormones for which they have receptors. Likewise, cAMP activated metabolic enzymes differ in structure and function in different target tissues.