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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-
Positive Feedback Loop- Active Labor
References
- 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
Abstract
Positive feedback is defined as intensifying a change in the body’s physiological condition rather than reversing it, or a deviation from a normal range, resulting in more change, moving farther away from the original range.
In Veronika’s project, a positive feedback loop that occurs with the human body: labor. The steps of labor are depicted by color coding oxytocin a red, gap cells as green, achieving homeostasis as blue, and oxytocin over producing as orange. A skeleton was also used to show where in the body the hormonal fluctuations were originating from, the placenta. A video of the skeleton’s lower abdomen was created to show the changing colors that correlated with the different steps of labor and the hormones involved. First the over production of oxytocin, this initiates the positive feedback system, or labor. Then in a green light oxytocin and estrogen then trigger gap cells to tell the muscles in the surrounding area to start contractions. The red again for another over production of oxytocin, followed by more intense contractions when the final push occurs before the fetus exits the mother’s body. After the fetus is born, the stimulus that initiated the positive feedback loop has halted, oxytocin is being regulated back to normal, and hormones are balancing out to achieve homeostasis post birth. Before homeostasis can be completed, the placenta birth also occurs, then the body can regulate hormones again, and it is depicted as a deep indigo color in the video/pictures above. The topic of positive feedback was covered, as well as a deep understanding of the topic covered by making a unique video with colors corresponding to the different steps labor takes as well as the hormones involved in labor.