This STEAM project will be focusing on a positive feedback loop that happens at the end of pregnancy to initiate labor. Positive feedback loops are not common in the human body. This is because they can become unstable and dangerous very easily. I was able to research some other human positive feedback loop, thanks to my peer review studies and was able to focus on my favorite positive feedback loop, labor. At this late stage of pregnancy the placenta is calling most of the shots, or at least secreting most of the hormones. The hormones that are in abundance during late pregnancy are progesterone and estrogen. Progesterone is playing many important roles, including keeping the smooth muscle of the uterus relaxed. This prevents early labor. But once the female body is ready, estrogen engages the first step in this series of positive feedback loops. Estrogen triggers myometrial cells to start making receptors for the hormone oxytocin. The red (cell balls and red light light) in my Steam project represent oxytocin. Oxytocin and estrogen trigger the process of gap cells that help create contractions (green cell balls and green lights represent contractions). This will let individual muscle cells contract, helping push that baby out. Baby, or the fetus, starts to help mom out by signaling more production of oxytocin and prostaglandins. This stimulates the uterus to contract more, thus causing a positive feedback loop. In my presentation, I have a skeleton model representing a woman in labor. There are a series of lights representing different hormones or reactions to the positive feedback loop. The first reaction of red light and red cells exiting the body is oxytocin. Followed by a green light and cells, representing contractions and pressure. This is the first step of the continuous loop stimuli. The blue light represents the fetus being born. The fetus is the trigger stimulation for the positive feedback loop. Once the fetus, the stimulant, makes its exit from the body the last bit of oxytocin stops secreting (red lights and smaller red ball cells). Regular hormones start to surface represented by the yellow light. The last bit of contracting and stimuli happens to exit the placenta, represented in the blue/purple color as the final step.
Below is the link to the Youtube video-
- Ando H, Sato T, Tomaru U, et al. Positive feedback loop via astrocytes causes chronic inflammation in virus-associated myelopathy. Brain: A Journal of Neurology. 2013;136(9):2876-2887. Accessed July 31, 2021. http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=90017803&site=eds-live
- Reproductive system, Part 4 – Pregnancy & Development: Crash Course A&P #43. YouTube. (2015, November 23). https://youtu.be/BtsSbZ85yiQ.
- Qin Li, Meissner TB, Fang Wang, et al. ELF3 activated by a superenhancer and an autoregulatory feedback loop is required for high-level HLA-C expression on extravillous trophoblasts. Proceedings of the National Academy of Sciences of the United States of America. 2021;118(9):1-9. Accessed July 31, 2021. http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=149206954&site=eds-live