Entry 4:The Small Intestine

This is my 4th entry on the Digestive System.I have posted quite a number of posts today as I am lagging in a few entries...I shall continue in the journey of food in the digestive tract.
The small intestine (also known as the small bowel) is the longest portion of the digestive tract - it is more than 6 meters long and is located within the middle of the abdomen. It has three sections, the duodenum, jejunum and ileum. Much of the small intestine is coiled and suspended in a thin layer of fat - which gives the intestine a lot of flexibility and mobility. Most substances in the food we eat need further digestion and must travel into the intestine before being absorbed. When it's empty, an adult's stomach has a volume of one fifth of a cup (1.6 fluid ounces), but it can expand to hold more than 8 cups (64 fluid ounces) of food after a large meal. By the time food is ready to leave the stomach, it has been processed into a thick liquid called chyme. A walnut-sized muscular valve at the outlet of the stomach called the pylorus keeps chyme in the stomach until it reaches the right consistency to pass into the small intestine. Chyme is then squirted down into the small intestine, where digestion of food continues so the body can absorb the nutrients into the bloodstream. Digestion of fats, proteins and carbohydrates contained in the foods you consume, is completed within the small intestine. The resulting nutrients produced are absorbed through the lining of the small intestine and transferred to the bloodstream. The small intestine is the site where most of the nutrients from ingested food are absorbed and is covered in wrinkles or folds called plicae circulares. The purpose of these wrinkles and projections is to increase surface area for absorption of nutrients. From the small intestine, undigested food (and some water) travels to the large intestine through a muscular ring or valve that prevents food from returning to the small intestine.

Information obtained from:
1)http://kidshealth.org/parent/general/body_basics/digestive.html
2)http://www.gesa.org.au/digestive-system/small_intestine.cfm
3)http://en.wikipedia.org/wiki/Small_intestine