1. www.buffalo.edu Abstract Introduction Materials and Methods Conclusion Literature Cited Results There are many different positive and negative feedback mechanisms in the endocrine system. There are more negative than positive. Positive and Negative feedback mechanisms. By: Mary and Jeremy Results Acknowledments There are two feedback mechanisms of the endocrine system. They are positive and negative feedback. One example of a positive feedback mechanism in the endocrine system is the production of oxytocin during labor. When the baby enters the birth canal the body produces the hormone oxytocin. Oxytocin stimulates labor contractions which in turn makes the body produce more oxytocin. This process goes on until the baby leaves the birth canal, which stops the oxytocin production and the labor contractions. One example of a negative feedback mechanism is how you sweat when your body temperature rises. Positive feedback: Negative feedback: Some times when the gland releases hormones they release to much. temperature is one negative part to the system, and regulation of blood calcium is an other one. Negative feedback regulates in every system in the body. Negative feedback occurs when the rate of the process decreases as the concentration of the product increases. The release of hormones is controled by a negative feedback mechanism. An example of how negative feedback works in the body can be showed by the endocrine system’s controls over the amount of sugar in the bloodstream. Insulin is a hormone the pancreas makes that maintains a normal amount of sugar in the bloodstream. Shortly after eating a candy bar, tiny sugar molecules enter the bloodstream raising the blood sugar levels. In response, the pancreas produces insulin that goes into the bloodstream. Now, the sugar molecules move out of the bloodstream and into the cells of the skeletal muscles, fat and liver. Then, the blood sugar levels return to normal. We are two biology students from Alden High School that are doing a study on positive and negative feedback mechanisms in the endocrine system. We are doing this for a project in our biology class. We are getting our information from years of other peoples research. Our goal is to help people to be more informed about the endocrine system. We also are explaining and giving examples of the different feedback mechanisms in the endocrine system. We used the internet to do most of our research. We used many different websites on the internet. An example of positive feedback can be found in childbirth and nursing. The hormone oxytocin stimulates and enhances labor contractions. Breastfeeding is a positive feedback mechanism. When you breastfeed the hormone prolactin is released from your pituitary gland. The prolactin makes the breast produce more milk. When you stop breastfeeding you stop producing so much prolactin therefore you stop producing so much milk. During childbirth the body produces the hormone oxytocin, which stimulates labor contraction. When the baby move toward the birth canal the pressure receptors in the cervix send messages to the brain telling it to produce oxytocin. The oxytocin get transported to the uterus through the bloodstream. The oxytocin stimulates the muscles in the uterine wall, which makes contractions stronger. When the baby leaves the birth canal the pressure receptors stop telling the brain to produce oxytocin. When this happens the oxytocin stops going to the uterus and contractions stop. We would like to thank our biology teacher Mr. Kasper for teaching us how to do this poster. He has been very support full of this project even when we weren't sure we could finish it. We would also like to thank the people who have done years of research before us and posted it on the internet. You guys helped us get accurate information quickly so we could put it on our poster. There are many others who have help us that I can't mention right now but thank you to all that helped us. http://www.simplymotherhood.com/services/page s/BreastfeedingFAQs.htm http://www.hormone.org/Endo101/page3.cfm http://faculty.clintoncc.suny.edu/faculty/michael.gr egory/files/bio%20102/bio%20102%20lectures/en docrine%20system/endocrin.htm http://www.vivo.colostate.edu/hbooks/pathphys/e ndocrine/basics/control.html