Hormones

Hormones are organic substances that are secreted by plants and animals and that function in the regulation of physiological activities and in maintaining homeostasis. They carry out their functions by evoking responses from specific organs or tissues that are adapted to react to minute quantities of them. The classical view of hormones is that they are transmitted to their targets in the bloodstream after discharge from the glands that secrete them. This mode of discharge (…

…periodic molting, or shedding, of the hard exoskeleton. Another insect hormone, called juvenile hormone, maintains the larval state. A decrease in juvenile hormone triggers the development of the adult characteristics. Plants also have a hormonal system, which includes auxins, gibberellins, and cytokinins, all of which promote growth. Plant hormones also include several growth inhibitors, which regulate such activities as the fall of deciduous leaves in autumn and the development of dormancy in buds and seeds.