Action_of_Hormones_jd_2 - Actions of Hormones on Target...

Actions of Hormones on Target Cells
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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.

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.