Physics of Urination and Digestion
Friday, February 2, 2018
Mammals maintain the flow of nutrition by various form of fluid such as urine, processed food, and feces. How do animals process and excrete the flow, from mice to elephants? In this talk, I will present that urine is accelerated by gravity in the urethra, which serves as a siphon in the urinary system. Larger animals such as elephants urinate as fast as their smaller counterparts, such as cats. Regardless of body size, the acceleration of fluid is also found in the process of defecation. Feces slide along the large intestine by a layer of mucus. Larger animals have thicker mucus layers that facilitate defecation. I will also present that gut contents mix by segmental contraction in the small intestine. The intestine contracts faster near the large intestine where the gut content is lighter. These studies shed light on non-invasive diagnoses of urinary and digestive diseases in humans and optimal transport strategies in soft tissue.
More information is in the BBC and CNN news
Patricia Yang is a Ph.D. candidate in mechanical engineering at the Georgia Institute of Technology, where she investigates problems at the intersection of fluid mechanics and biology, and in particular, excretion and digestion. Before graduate school, she received her bachelor’s degrees in physics and engineering from National Taiwan University. She was the recipient of the East Asia and Pacific Summer Institute Award from the National Science Foundation, the College Student Research Fellowship from the Ministry of Science and Technology in Taiwan, and the 2015 Ig Nobel Prize in Physics. Her work has been featured on National Public Radio, in National Geographic Daily, and in The Times in London. In addition to conducting research, she teaches fluid mechanics at all levels, from elementary school to college.