Have you heard the word Rugae before? I do not mean Reggae the beat, I am ttalking about the prominent ridges or folds that shows up on the mucous membrane lining the stomach, bladder, and some other organs.
In the stomach, these rugae are prominent folds in the mucosal lining which are elastic and they can stretch to allow for more content into the stomach than the normal size of the stomach without any content in it. Aside from elasticity, Rugae plays a very important role in digestion as it increases the surface area of stomach lining creating turbulence in the stomach so as to allow the food to mix with the digestive enzymes secreted in the stomach as well as promoting the breaking down of food into smaller molecules during digestion. It is present everywhere around the stomach including the exit region of the stomach, slowing down the passage of food out of the stomach thereby giving the stomach enough time to digest the food.
The stomach isn't the only place where rugae can be found in the body like I stated at the beginning of this post, it can also be found in areas such as the vagina. In the vagina, the fold contributes to the unique anatomy and function of the vagina, trapping moisture, and creating a lubricating surface which facilitate sexual intercourse as well as protect the lining of the vaginal canal from irritation.
Similar to how the Rugae works in the stomach, it allows for the expansion of the vagina during sexual intercourse as well as during child birth but then the rugae can disappear after childbirth because of the level of elasticity and the pressure asseted on them by the child during the process but after the birth, the vagina starts to heal and at about the third postpartum week, the rugae begins to reappear.
Although childbirth can make the Rugae dissappear temporarily, there can be more complex reaction with age. With age, Estrogen production reduces, leading to the thinning of the vaginal wall as well as a permanent loss of the vaginal rugae causing the vaginal to lose its elastic properties causing it to be more sensitive to pain.
Similar to the stomach and the vagina, Rugae is present in the bladder, helping it to expand and contract so as to help it store urine and empty its content. It also allow for the re-absorption of nutrients and electrolyte from the bladder which is important in maintaining fluid balance. Another place with fold is the luminal wall of the gall bladder. The liver produces bile which is stored in the gallbladder, which has folds known as plica. The fold allows the gallbladder to expand when storing and contract when releasing bile based on dietary fat intake. It also mixes bile together to ensure that the bile being released is the properly mixed.
The anal canal and rectum also have mucus membrane folds that allows for elasticity. The mucus membrane releases mucus which lubricates the rectum and anal canal allowing for easy passage of waste. Rugae is also found in the anterior part of the pallet and this rugae is unique for each individual and they do not change over the lifetime of each individuals.
In essence, rugae showcase the marvels of design and functionality across different organs, emphasizing their versatile roles in maintaining health and supporting various physiological processes.
Reference
https://www.imaios.com/en/e-anatomy/anatomical-structure/gastric-folds-1541092908
https://www.imaios.com/en/e-anatomy/anatomical-structure/vaginal-rugae-1541216232
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3826037/
https://www.kenhub.com/en/library/anatomy/stomach-histology
https://www.kenhub.com/en/library/anatomy/the-anal-canal
https://healthinfo.healthengine.com.au/gastrointestinal-system
