human digestion process

There are seven basic steps to the digestive system. They are:
1. eating and chewing,
2. swallowing and passage through the esophagus
3. digestion in the stomach
4. further digestion involving the liver and pancreas
5. absorbing nutrients in the small intestine
6. absorbing water in the large intestine
7. excretion of the waste products

* Steps of the digestive system in detail:
Food is placed in the mouth and chewed, and mixed with saliva from the salivary glands. The tongue and epiglottis direct the food as it is swallowed.

The food travels to the esophagus (which is lined with a thick mucus) and moves into the stomach.

In the stomach, the food is mixed with acids that break its materials down (the stomach has a lining to protect itself from the acid it produces). Once the food is broken down it enters the small intestine through the pyloric valve.

In the upper part of the small intestine, the duodenum, bile produced by the liver is added from the gall bladder to the mixture (called chyme) to further break down nutrients and neutralize some of the remaining stomach acid. The pancreas is also located here and adds several necessary digestive enzymes.

The lower part of the small intestine (the jejunum and ileum) is lined with millions of fine protuberances called villi, which absorb nutrients out of the food, and into the bloodstream.

Once most of the nutrients are removed, the remaining materials move to your large intestine. In the large intestine, most of the water and some compounds such as vitamins are removed. Fermentation may also release some necessary nutrients. The large final section is called the colon.

The mostly-dehydrated waste is pushed through the colon to the rectum (which has a a strong muscle called the sphincter) and leaves the body.