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Action_of_Hormones_jd_2 - Actions of Hormones on Target...

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Actions of Hormones on Target Cells Graphics are used with permission of: Pearson Education Inc., publishing as Benjamin Cummings (http://www.aw-bc.com) Page 1. Actions of Hormones on Target Cells Hormones influence their target cells by binding to specific receptors. The hormone-receptor interaction initiates the process of transforming the chemical message into a cell response. Page 2. Goals/ What You Need to Know Goals To learn about hormone receptors. To describe common second messenger systems and transcription factors. To review insulin. To understand that hormones induce changes in cellular metabolism. What You Need to Know That changing the shape of a molecule can activate or inactivate it. The terminology of carbohydrate, lipid and protein metabolism. The difference between the absorptive and postabsorptive states of the body. Page 3. Target Cell Responses to Hormones Hormones bind with receptors to initiate the cellular response to a chemical signal. Target cells convert the signal into a biochemical change inside the cell. Via second messenger systems. Via direct gene activation. Cells respond to this stimulus in several different ways: 1. Cause contraction of muscle tissue. 2. Secretion of cellular products. 3. Effecting ion exchange through channels. 4. Cause synthesis of new peptides and proteins. 5. Cause breakdown of storage molecules. Receptors are complex proteins that only respond to specific hormones. Receptors for water-soluble hormones are found on the plasma membrane. Receptors for lipid-soluble hormones are found in the cytoplasm or the nucleus. Receptors will down-regulate and decrease sensitivity when there is prolonged exposure to high levels of a hormone. Receptors have the ability to up-regulate and increase sensitivity in response to sustained low levels of a hormone. Not all cells have receptors for all hormones and some cell respond differently to different concentrations of hormone. **Now is a good time to go to the quiz question #1. Click the quiz button on the left side of the screen. Click on the scrolling page list at the top of the screen and complete question 1. When you are finished you can click the return from link button on the left side of the screen to return to the topic.
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Page 4.Water-soluble Hormones and Receptor Responses The water soluble hormones are the peptide and catecholamines. They bind to receptors on the outside surface of the cell.
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