Our Digestion System

Picture from Wikipedia
 When we eat and chew our food, the saliva makes the food soft and easy to swallow. The saliva is alkaline and contains enzymes that break down the starch molecules. Therefore, it is important to chew well when eating vegetables to get the maximum amount of nutrients they contain.

It is best to chew the food for a while. Then you also experience more of the taste and the joy of eating :-)

From the mouth, the food travels down the esophagus to the stomach. In the stomach, the food mixes with gastric juices, which starts to break down the meal and remove bacteria that might be in the food. The gastric juices have a low pH, which also activates the enzymes that break down protein. In addition to the gastric juices, muscles in the walls of the stomach also help break down the food to a thick liquid, called chyme.

After some hours, the stomach empties the liquid into the duodenum, the first part of the small intestine. It empties slower with high levels of fat in the meal, because it takes a longer time to digest fat in the small intestine than it does with carbohydrates and proteins. This delay is the reason why we often feel full longer after a fatty, rich meal.

In the small intestine, the liquid continues to break down, so that the body can absorb the carbohydrates, proteins and fats. Juices from the pancreas, liver and gall bladder help to digest the food so the body can absorb all the nutrients.

The pancreas produces enzymes, which further break down the macro-nutrients. The secretion of pancreas juice begins when the food comes to the small intestine. The pancreatic juice is alkaline and its purpose is to neutralize the gastric acid from the stomach.

The neutralizing is important to avoid damage from the gastric acid on the mucus membrane in the small intestine and to activate the enzymes from the pancreas. The pancreas also produces hormones like insulin and glucagon.

Bile is further necessary for absorption of fat. Bile is produced in the liver and is stored in the gall bladder. When we eat, it secretes into the duodenum. The pancreas and the gall bladder have the same exit, in the upper part of the small intestine. The bile emulsifies and finely divides the fat.

Most of the nutrients from food is absorbed in the small intestine. From the intestine, they pass over to vena porta where the nutrient-rich blood goes directly to the liver. Except for the fat, that transfers over to the lymph vessels and is stored in fatty cells. The body absorbs most of the substances independently of whether the body needs them or not, except for calcium and non-heme iron, where the absorption is regulated to what the body needs.

In the liver, the blood is filtered and distributed before the nutrients are sent out to the cells in the body. The concentration of glucose is especially regulated closely. Surplus glucose is stored as glycogen in the liver and muscles, so the blood sugar does not rise too high. The glucose can also be stored in fatty cells, although it is converted to triglycerides.

Food that the body cannot use, like diet fiber, goes further to the large intestine where carbohydrates such as cellulose and starch are broken down by enzymes. Some of the byproducts of the break down are short-chain fatty acids that are absorbed by cells in the large intestine. These acids are essential for the well-being of the large intestine and one of the reasons that a diet rich in fruit and vegetables is recommended. Another important function to the large intestine is absorption of water.

*Our digestion system is a marvelous world that makes many daily miracles, transforming solid foods into small substances and energy that nourishes our bodies so we can live happy, healthy lives. By drinking clean water and eating a healthy diet that includes foods rich in fiber, like fruit, vegetables and whole grains, you help support your digestive system and keep your body young and alive.

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