![]() Tissues vary in their response to epinephrine because they vary in their receptors, their signal temperatures, or their signal transduction pathways. All these effects prepare the body for "fight or flight." Explain how these multiple effects are possible. For example, epinephrine can cause the release of glucose from liver cells, dilate blood vessels to skeletal muscles, and constrict intestinal blood vessels. ![]() One hormone can have several different effects. There, the receptor portion of the complex alters transcription of particular genes by interacting with a specific DNA-binding protein or response element in the DNA. When a steroid hormone binds to its cytosolic receptor, a hormone-receptor complex forms, which moves into the nucleus. Steroid hormone receptors are located in the cytosol prior to binding to a hormone. ![]() See page 997 in your text for the labeled figure. Explain the action of this steroid in the following figure. Lipid-soluble hormones, such as estradiol, bind to intracellular receptors. See page 997 in your text for the labeled figure and explanation. Use the following figure to explain the signal transduction pathway for epinephrine. The net result is that the liver releases glucose into the bloodstream, providing the fuel you need to deal with short-term stress. Activation of protein kinase A by cAMP leads to activation of an enzyme required for glycogen breakdown and inactivation of an enzyme necessary for glycogen synthesis. The binding of hormone to receptor triggers a cascade of events involving synthesis of cyclic AMP as a short-lived second messenger. What are the two intracellular responses in the liver to epinephrine? How do these help the body deal with short-term stress? When epinephrine reaches the liver, it binds to a G protein-coupled receptor in the plasma membrane of target cells. What endocrine gland secretes epinephrine? Adrenal glands secrete epinephrine. Use the diagram below to review basics of signal transduction pathways. Water-soluble MoS-exocytosis, MoT- travel freely in bloodstream, LoR- cell surface signal receptors, Eg- Epinephrine Lipid-Soluble MoS- diffuse across the membranes of endocrine cells, MoT- bind to transport proteins that keep them soluble in the aqueous environment of the bloodstream, LoR- intracellular signal receptors, Eg-thyroxine, testosterone 14. Name the 2 hormone types, their method of secretion, mode of travel in bloodstream, location of receptors, and exmples. This is different from steroid hormones that are lipid-soluble because water-soluble hormones cannot pass through the membrane of cells. Where are the receptors for the water-soluble hormones found? Receptors for water-soluble hormones are found on the cell surface. Where are the receptors for lipid-soluble hormones found? Receptors for lipid-soluble hormones typically reside in the cytoplasm or nucleus. Recall that target cells have receptors for specific hormones. What are the three major classes of molecules that function as hormones in vertebrates? See figure 45.4 11. Secreted by endothelial cells in blood vessels and results in vasodilation (increased blood flow) prostaglandins modified fatty acids local regulator that is secreted by most tissues and perform a variety of physiological functions 10. cytokines polypeptide local regulator - communication between immune cells growth factors polypeptide local regulator -promote growth, division and development nitric oxide gas functions as local regulator and neurotransmitter. See page 994 in your text for the labeled figure and explanations. Figure 45.2 in your text shows five different types of signals. Example- the compound secreted by termites that results in others "following" 8. Example- acetylcholine pheromones Pheromones are chemicals that are released into the external environment to affect members of the same species. Neurotransmitters At synapses, neurons secrete molecules called neurotransmitters that diffuse a very short distance to bind receptors on the target cells.
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