Evolution of Endocrine Systems

Evolution of Endocrine Systems - Endocrine Systems and...

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Evolution of Endocrine Systems | Most animals with well-developed nervous and circulatory systems have an endocrine system. Most of the similarities among the endocrine systems of crustaceans, arthropods, and vertebrates are examples of convergent evolution . The vertebrate endocrine system consists of glands (pituitary, thyroid, adrenal), and diffuse cell groups scattered in epithelial tissues . More than fifty different hormones are secreted. Endocrine glands arise during development for all three embryologic tissue layers (endoderm , mesoderm , ectoderm ). The type of endocrine product is determined by which tissue layer a gland originated in. Glands of ectodermal and endodermal origin produce peptide and amine hormones; mesodermal-origin glands secrete hormones based on lipids.
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Unformatted text preview: Endocrine Systems and Feedback Cycles | The endocrine system uses cycles and negative feedback to regulate physiological functions. Negative feedback regulates the secretion of almost every hormone. Cycles of secretion maintain physiological and homeostatic control. These cycles can range from hours to months in duration. Mechanisms of Hormone Action The endocrine system acts by releasing hormones that in turn trigger actions in specific target cells . Receptors on target cell membranes bind only to one type of hormone. More than fifty human hormones have been identified; all act by binding to receptor molecules. The binding hormone changes the shape of the receptor causing the response to the hormone. There are two mechanisms of hormone action on all target cells....
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Evolution of Endocrine Systems - Endocrine Systems and...

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