Guided Reading Qs (Do these before the Mastering Assignment.) L05: Cell Signaling with Hormones (Reading 26.1-26.3, 26.7-26.9 plus a 13-min podcast interview, and an article on Sakai, “The Origins of Transgender”) Reading Objectives •Differentiate between chemical and electrical signaling to cells •Describe how the two types of chemical signaling mechanisms affecting target cells differently. •Apply the two mechanisms of chemical signaling to insulin signaling and sex hormone signaling. •Explain the consequences of endocrine disruptors. •Explain how testosterone and estrogen affect gender development. Modules 26.1-2 1. What two type of signals does the body use to communicate? Chemical and electrical signals How do they affect different responses in the body? Hormones coordinate the body’s responses to stimuli such as dehydration, low levels of blood glucose, and stress. The nervous system is well adapted for directing immediate and rapid responses to the environment. 2. What does a target cell have that allows it to respond to a hormone secreted from a distant gland that a non-target cell is lacking? Receptors that recognize the specific signal 3. List and describe the three stages of hormone signaling: Reception: occurs when a hormone binds to a specific receptor protein on or in the target cell Signal Transduction: converts the signal from one form to another Response: a change in the cell’s behavior 4. Are hormone receptors on the plasma membrane or inside cells? The receptor proteins for most water soluble hormones are embedded in the plasma membrane 5. Draw a quick diagram outlining the differences between: water-soluble hormone signaling vs. lipid soluble hormone signaling6. Why can steroid hormones pass through the plasma and nuclear membranes? Because they are lipophilic Module 26.3 7. Scientific Thinking: What hypothesis were the scientists testing? That long term exposure to even low levels of atrazine during development would hav negative effects on reproductive function in amphibians. What were the control and experimental groups? The control group was the group of frogs that were not exposed to the atrazine, while the experimental group was the group of frogs that were exposed. What was the independent variable? The atrazine exposure Dependent variables? The negative effect on reproduction functions in the frogs What were the results? More males in the atrazine-exposed group experienced testosterone deficiencies than did those in the control group This was a controlled laboratory study—does it have any implications for the real-world environment? Yes because the levels of atrazine used in the studies were consistent with environmental conditions for some amphibians in the wild. It suggest that part of the decline may be due to a lack of success in the mating. Module 26.7: 8. What are the three major categories of sex hormones? Do males have estrogen?YES Do females have testosterone? YES Explain differences. Females have a high ratio of estrogens to androgens while males have high ratio of androgens to estrogens. The sex hormones are produced by the gonads (ovaries and testes) but affect cells in distant parts of the body. What are some of the distant targets affected? The test produce androgens, which allow for the development of secondary sex characteristics and the production of sperm cells. The ovaries produce estrogen and progesterone, which cause secondary sex characteristics, regulate production of eggs, control pregnancy, and prepare the body for childbirth. 9. Spotlight on human biological variation: Androgen insensitivity. What happens when testosterone is made but cannot bind its receptor inside the cell? Target cells are insensitive to testosterone present in the blood resulting in androgen insensitivity syndrome and male external genitalia and female ovaries do not develop.“Intersex is a general term used for a variety of conditions in which a person is born with a reproductive or sexual anatomy that doesn’t seem to fit the typical definitions of female or male… Intersex is a socially constructed category that reflects real biological variation. To better explain this, we can liken the sex spectrum to the color spectrum…. So nature doesn’t decide where the category of “male” ends and the category of “intersex” begins, or where the category of “intersex” ends and the category of “female” begins. Humans decide.” This site has many helpful ideas if you want to learn more https://isna.org/faq/what_is_intersex/ 10. What are some ways testosterone affects other animals besides humans? Testosterone causes aggressive male behavior in elephant seals, increased singing in male songbirds, and the development of antlers in male deer and elk. Modules 26.8-9 11. What organ secretes insulin and glucagon? The pancreas What are the target cells of insulin? What affect does insulin have on cells? Adipose tissue, skeletal muscle, and the liver. Insulin binds to receptors on target cells, a cascade of phosphorylation leads to remade glucose channels begin inserted into the membrane. What are the target cells of glucagon? What affect does glucagon have on target cells? The liver, cardiac and skeletal muscles, adipose tissue, and other tissues. Stimulates glycogenolysis (breakdown for glycogen into glucose) in liver; stimulates gluconeogenesis (conversion of non- carbohydrates into glucose); stimulates lipolysis (breakdown of stored fat) in adipose tissues fat is released and used as a fuel sources, instead of glucose. 12. Diabetes (as a group of diseases) affects 1 in 11 Americans. What is diabetes? A serious hormonal disorder caused by the blood’s inability to produce or use insulin, thereby decreasing the absorption of glucose from the blood. 13. Compare and contrast the differences in hormone signaling defects in type 1 vs type 2 diabetes: In type 1, the pancreas does not produce enough insulin. Without sufficient insulin, target cells do not receive the signal that leads to glucose transporters being moved to the plasma membrane. In type 2, insulin is produced, but the insulin signal is not relayed normally inside the target cells. Pancreatic beta cells adapt to the defective signaling by producing even greater amount of insulin. What condition occurs if too much insulin is produced or injected? Hypoglycemia, which could lead to convulsions and
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