Structural Biochemistry/Cell Signaling Pathways/Hormonal Signaling

Hormonal Signaling
Hormone is an important signal molecule that is used by both]]]] plants and animals. “Hundreds of hormones can regulate a wide variety of physiological functions, including growth and development, rates of body processes, concentrations of substances, and responses to stress and injury” (Becker, et al. 416). Distance traveled by hormones can vary depending on hormones’ life span. Some hormones can last only seconds in blood stream, indicating short distance regulation. Hormones that are long distance traveler can have life spans ranging from minutes to even hours. Hormones also have different chemical properties. Generally, “hormones can fall into four different categories: amino acid derivative, peptides, proteins, and lipid-like hormones such as steroids” (416). Difference in their chemical properties allows hormones to bind to different receptors thereby regulating different pathways. For example, adrenergic hormones bind to a family of G proteins to increase the concentration of glucose in muscle cells (416-417).

Hormonal signaling follows the following steps:
 * 1) Biosynthesis of a particular hormone in a particular tissue
 * 2) Storage and secretion of the hormone
 * 3) Transport of the hormone to the target cell(s)
 * 4) Recognition of the hormone by an associated cell membrane or intracellular receptor protein.
 * 5) Relay and amplification of the received hormonal signal via a signal transduction process: This then leads to a cellular response. The reaction of the target cells may then be recognized by the original hormone-producing cells, leading to a down-regulation in hormone production. This is an example of a homeostatic negative feedback loop.
 * 6) Degradation of the hormone.

Reference
Becker, Wayne M, et al. The World of the Cell. 7th ed. New York: Pearson/Benjamin Cummings, 2009. Print. http://www.news-medical.net/health/Hormones-as-a-Signal.aspx