The digestive system is crucial for supplying your body with the nutrients it needs to survive. The food we eat must be changed into a smaller, more usable form through a process called digestion, which is the role of the digestive system. The hollow organs comprising the digestive system include the mouth, esophagus, stomach, small and large intestine, rectum and anus. The solid organs which also assist with digestion include the liver, pancreas and gallbladder.
Digestion begins as soon as food enters the mouth. Digestive enzymes secreted in the mouth help begin breaking down carbohydrates. Next, food is swallowed into the esophagus, where peristalsis, which is the contraction of organ walls in the digestive tract that propels food downwards through the organ, carries the food to the stomach. The stomach serves as storage, but also mixes the food with acids it produces to begin the breakdown of proteins. Once the this process is complete, peristalsis empties the contents into the small intestine.
The small intestine is the area where the majority of digestion occurs. Digestive enzymes that breakdown fats, proteins and carbohydrates are secreted by the lining of the intestines. Also, the pancreas produces enzymes as well that mix with the food in the intestines to break it down, and the liver produces bile. Bile is stored in the gallbladder, and when food hits the small intestine, it is released into the intestine to help dissolve fats. After food is properly broken down, digested molecules, water and minerals are all absorbed from the intestine walls with the help of micro villi and into the bloodstream. Any leftover waste products are pushed into the colon, until they are finally expelled as feces through the rectum and anus.
Once the nutrients leave the small intestine and enter the bloodstream, they travel to certain parts of the body, where they're either stored or changed into other forms. Proteins travel to all parts of the body to help build cells, while carbohydrates are broken down into simple sugars and stored in the liver, where it can be released for use as energy. Fats travel to various storage center throughout the body.