Our digestive system consists of the gastrointestinal tract (also called the digestive tract), the liver, the pancreas and the gallbladder. The digestive tract connects the mouth with the rectum. In between are the so-called hollow organs, which are connected to a winding tube. These hollow organs include the mouth, esophagus, stomach, small intestine, large intestine and anus. The liver, pancreas and gallbladder are among the solid organs of this tract.
Why is our digestion so important?
Our digestion is responsible for absorbing important vitamins and other nutrients that we need for our health and a functioning body. These substances include, for example, proteins, fats, carbohydrates, vitamins, minerals and, above all, water. Our digestive system breaks down the nutrients into the smallest parts and then delivers them to all body regions. From this, the body can then generate energy and growth, which it can use, for example, for the repair of broken body cells.
How does our digestive system work?
Every organ in our gastrointestinal tract helps to either move or crush food and fluids. Once the food has been divided into its individual nutrients, the body can absorb it and transport it to where it is needed. The large intestine absorbs the last nutrients and the waste products of digestion become stools. The nerves and hormones help to coordinate and control the digestive process.
How does the ingested food move through the gastrointestinal tract?
The process in which food is moved through the gastrointestinal tract is called peristalsis. The hollow organs of the tract have a muscle layer that allows the organ walls to move. This movement pushes the food and fluids through the gastrointestinal tract and mixes them together. If the mixture has passed through a muscle, it contractes and pushes it into the next organ.
When swallowing, the tongue pushes the food into the throat. A small tissue lobe, also called epiglottis, folds over the trachea and thus prevents suffocation by food or liquids. These then end up in the esophagus.
After swallowing, all processes of digestion proceed automatically. Our brain sends signals to the esophagus and peristalsis begins.
The lower sphincter of the esophagus
When the ingested food has crossed the esophagus, the lower sphincter of the esophagus opens and leaves it in the stomach. After that, this muscle closes again so that the mixture in the stomach does not flow back into the esophagus.
In the stomach, the food and fluids are mixed with the digestive juices. After this process, the mixture continues to enter the small intestine.
The Small Intestine
The muscles of the small intestine mix the incoming food with the own digestive juices and those of the pancreas and the liver. Through the organ walls, the small intestine absorbs water and digested nutrients and releases them into the bloodstream. After this process, the waste products continue to migrate into the large intestine.
The large intestine
The waste products of the previous digestion end up in the large intestine. These waste products consist of undigested parts of food and fluids, as well as older cells from the previous organs. The large intestine absorbs the remaining water and thus converts the liquid waste products into stools. This is then pressed further to the rectum.
The rectum is the lower end of the large intestine. Here, the chair is “temporarily stored” until it leaves the body during bowel movements.
How is the food broken down into its individual parts?
The further the food moves through the gastrointestinal tract, the more it is crushed. This is done by:
- Movement: for example by chewing in the mouth and mixing and squeezing in the organs
- Digestive juices such as stomach acid, bile and various enzymes
The digestive process is started in the mouth. Here the food is crushed by chewing. The salivary glands produce saliva that moisturizes the food so that it can move more easily through the esophagus. In addition, the saliva contains enzymes that can already crush the strength of the food.
Through the esophagus, the food is transported into the stomach.
The glands in the stomach produce stomach acid and enzymes that further crush the food. Through the movement in the stomach, the food is mixed well with the juices.
Our pancreas produces a digestive juice with whose enzymes carbohydrates, fat sands and proteins can be broken down. Through small tubes, this digestive juice enters the small intestine.
Our liver is the producer of bile juice, which breaks down some vitamins and fats. The bile juice is delivered via the bile ducts for digestion into the small intestine, or for caching into the gallbladder.
In the gallbladder, the bile juice is stored between meals. From here, the bile can be delivered to the small intestine for digestion.
The Small Intestine
The small intestine mixes its own digestive juices with those of bile and the liver to complete the breakdown of proteins, carbohydrates and fats. The small intestine contains enzymes that are responsible for the breakdown of carbohydrates. Furthermore, the small intestine draws water from the bloodstream and contributes it to the food mixture to speed up the digestive process. Afterwards, the small intestine absorbs this water with the nutrients.
The large intestine
The large intestine removes as much of the remaining nutrient-rich water as possible from the mixture. The bacteria in the large intestine break down the remaining nutrients and form vitamin K. The unused fabrics become stools.
What happens to the absorbed nutrients and vitamins?
Most nutrients are absorbed in the small intestine. Our circulatory system absorbs these substances and takes them to where they are needed or stored. Certain cells help the nutrients pass through the intestinal mucous membranes and thus guide them into the bloodstream. For example, our blood delivers simple sugars, amino acids, glycerin and some vitamins and salts to the liver. The liver stores, processes or supplies the nutrients where they are needed.
The lymphatic system, a network of vessels with white blood cells that protects us from infection, absorbs fatty acids and vitamins.
The body uses the sugar, the remaining amino acids, fatty acids and glycerol for energy gain, cell growth and cell repair.
How is the digestive process controlled?
Hormones and nerve cells work together to coordinate our digestive process. The brain and the digestive tract always exchange information about the current status of digestion.
Cells responsible for our stomach and small intestine generate hormones that control the function of our digestion. These hormones ensure that there are enough digestive juices at the right time and tell our brains whether we are hungry or full.
The pancreas also generates hormones that perform important digestion tasks.
Some nerves connect our central nervous system to our digestive tract, allowing our brain to coordinate digestive processes. For example, when we see or smell food, the brain gives the command to our salivary glands to produce saliva.
In addition, there is the enteric nervous system (ENS). This is located inside the walls of our gastrointestinal tract. When the walls of the organs are stretched outwards by food, the ENS releases liquids and substances that accelerate or delay both the digestion and the movement of the food. Furthermore, these nerves are responsible for the movement of the organ walls.