what happens to partially digested food after it leaves the stomach, up to the stage where it leaves the small intestine?
Since this is not my area of expertise, I searched Google under the key words "process of digestion steps" to get these possible sources:
https://www.google.com/search?client=safari&rls=en&q=process+of+digestion+steps&ie=UTF-8&oe=UTF-8
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
http://www.hackcollege.com/blog/2011/11/23/infographic-get-more-out-of-google.html
After partially digested food leaves the stomach, it enters the small intestine where further digestion and absorption take place. The partially digested food exits the stomach through a muscular valve called the pyloric sphincter, which regulates the flow of food into the small intestine.
To understand what happens to partially digested food in the small intestine, it is important to know how the small intestine is structured. The small intestine is a long, coiled tube with three distinct sections: the duodenum, the jejunum, and the ileum.
1. Duodenum: This is the first and shortest section of the small intestine. It receives partially digested food from the stomach, as well as digestive juices from the liver and pancreas. In the duodenum, several enzymes break down proteins, fats, and carbohydrates into smaller molecules that can be absorbed by the body.
2. Jejunum: The jejunum is the middle section of the small intestine. It continues the process of digestion and absorption. The inner wall of the small intestine contains numerous small, finger-like projections called villi, which increase the surface area for absorption. The digested food, now in the form of nutrients, is absorbed through the villi into the bloodstream.
3. Ileum: The ileum is the final section of the small intestine. It completes the absorption of nutrients, including vitamins and minerals. Any remaining undigested food, waste materials, and non-absorbed substances continue to move through the small intestine.
As the partially digested food progresses through the small intestine, it mixes with digestive enzymes, bile, and other fluids. The enzymes further break down the food, primarily into smaller molecules that can be absorbed by the intestinal lining and transported into the bloodstream for use by the body.
By the time the partially digested food reaches the end of the small intestine (ileum), most of the nutrients it contains have been absorbed, leaving behind mostly indigestible waste products such as fiber, some undigested carbohydrates, and certain waste materials from the breakdown of red blood cells, dead cells, and bacteria.
Ultimately, the remaining waste materials move into the large intestine (colon) for further processing, absorption of water, and the formation of feces, which will eventually be eliminated from the body through the rectum and anus.