The intestine is an important part of our digestive system, which consists of two main parts: The small intestine and the large intestine. It processes the food we eat every day and absorbs the nutrients. It also ensures that harmful substances are excreted. The intestines are home to billions of beneficial bacteria. An intact intestinal flora is therefore particularly important for our digestion and for a strong immune system. The gut even communicates with the brain and can therefore influence our well-being. So there are many good reasons to pay attention to good gut health.
The human intestine is a fairly long tube that winds its way through the entire abdominal cavity. It starts at the stomach and extends to the rectum, the anus. The intestine is divided into different sections that are responsible for different tasks. The small intestine is particularly important for food utilization. In it, the nutrients that we take in with our food are broken down into usable components and then absorbed into the body via the wall of the small intestine. These nutrients include carbohydrates, fats and proteins. When they are broken down into individual components, the body can use them to generate energy and for its metabolism.
However, the intestine is also home to countless invisible co-inhabitants – namely billions of different bacteria that form the intestinal microbiota. This is unique for every person! Every person has a different composition of microbiota in the gut, which is also influenced by our diet. The tiny microbes are important so that the body can better defend itself against pathogenic germs. In addition, some microorganisms in the intestine produce vitamins, for example vitamin K (for blood clotting) and various B vitamins such as B1, B2, B5, biotin or folic acid or messenger substances for the brain such as dopamine and GABA.
Microbiome diagnostics in prevention — does it make sense?The intestine also produces a number of hormones. They stimulate the formation and release of bile and pancreatic juices, which play an important role in digestion. These hormones include gastrin (production of stomach acid), leptin (fat absorption) and ghrelin (“hunger hormone”). A large proportion of immune cells (approx. 70 percent of the immune cells in the human body) are also found in the intestine. It is considered the largest immunological organ in our organism and is an important pillar of our immune defense.
If your bowels are not functioning and working properly, your well-being can suffer. Most people are probably familiar with unpleasant digestive problems such as flatulence, diarrhea or constipation. Various diseases can also develop in the intestine, for example intestinal polyps, irritable bowel syndrome (IBS ), chronic inflammatory bowel diseases(ulcerative colitis, Crohn’s disease) or bowel cancer. A balanced, varied and wholesome diet is the best recipe for keeping your gut healthy.
In both men and women, the intestine is located in the region below the stomach and fills almost the entire abdominal cavity. It is many meters long and runs through the abdominal cavity in the human body in several curves and snakes.
The intestine can be roughly divided into two main sections:
The intestine consists of two main sections – the small intestine and the large intestine. These can in turn be divided into further subsections. The parts of the intestine have different “jobs” to do.
In the small intestine, the food pre-digested in the stomach is broken down further. The body can now absorb the resulting nutrients into the blood via the mucous membrane of the small intestine. Organs and tissues receive these nutrients with the blood flow and can then use them for their metabolism.
The inner wall of the small intestine is heavily folded and therefore has a very large surface area (the size of two tennis courts). This principle of “surface enlargement” ensures that sufficient quantities of nutrients can be absorbed, which the organs and tissues need for their activity. There are also small protrusions on the mucous membrane of the small intestine, known as intestinal villi. Incidentally, they are absent in the large intestine. These intestinal villi are primarily responsible for the absorption of nutrients into the body.
The small intestine is about three to five meters long and can be divided into three sections:
Anatomy of the small intestine
In the right lower abdomen, the small intestine merges into the large intestine. This is about one to one and a half meters long and “frames” the small intestine like a square. There is an ascending part(ascending colon), a horizontal part(transverse colon) and a descending part (descending colon).
The descending part of the colon makes a slight S-curve in the left lower abdomen. This section is called the sigmoid colon (also known as the sigmoid colon or sigmoid colon). The rectum is connected to the sigmoid colon. Finally, there is the anal canal and anus – the connection between the bowel and the outside.
The large intestine has a larger diameter than the small intestine – hence its name. It has these sections:
Structure of the large intestine
The intestine has a mucous membrane that lines its interior like a “wallpaper”. Our body absorbs the broken-down nutrients into the blood via the intestinal mucosa. Intestinal villi on the mucous membrane help with the absorption of nutrients. The bloodstream is the means by which nutrients are transported to all organs and tissues.
The intestinal wall itself has strong intestinal muscles. It is important so that the transportation of the food slurry does not come to a standstill. The intestine also has many nerves that transmit stimuli. This is also the reason why stress or anger can affect the intestines. Digestive problems such as flatulence, diarrhea or constipation can be the unpleasant consequences. The psyche and digestion are therefore closely linked.
The intestine is also home to many billions of intestinal bacteria that we can neither see nor feel in everyday life. They form the intestinal microbiota. The intestinal microbiota normally consists of “good” bacteria that are beneficial to health. However, “pathogenic” bacteria can also colonize, which can cause various diseases.
However, various influences can cause the intestinal microbiota to become unbalanced. For example, antibiotics kill disease-causing but also protective bacteria.
The intestine is also a “home” for immune cells, which are an essential part of the immune system. Researchers now assume that these immune cells are also connected to our brain via various messenger substances. The term “gut-brain axis” describes this connection quite well. Behind this is a complex system that exchanges information via various channels. The intestinal microbiota is also involved in this communication.
For example, neurological diseases such as dementia, which mainly affect the brain, could also be linked to the gut. Intestinal bacteria, for example, produce substances that can also affect the brain.
The most important task of the intestine is to process the food we eat. All organs and tissues in our body – from the heart to the brain – need a wide variety of nutrients, vitamins and minerals every day for their energy metabolism. This is the only way they can work well and fulfill their tasks. The intestine helps to further break down the food that comes from the stomach. This means that the necessary nutrients are available for our body.
Another task of the intestine is to transport those food components that we cannot digest and utilize out of the body via the stool. The intestine is therefore not only a good “recycling plant”, but also serves as a kind of “garbage disposal”.
From the stomach, the chyme arrives in the small intestine and remains there for several hours. Special enzymes – these are small “biocatalysts” – break down the food components into nutrients that the organism can utilize and use for its metabolism. The pancreas, for example, produces these enzymes for digestion. They reach the small intestine with the digestive juices. In addition, there is bile from the gallbladder and intestinal secretions, which help the enzymes to “break down” the food.
The enzymes break down carbohydrates into sugar, proteins into amino acids and fats into fatty acids. Our body also absorbs vitamins and salts via the mucous membrane in the small intestine and transports them to other organs and tissues via the bloodstream. The intestinal villi in the small intestine have the task of helping with the absorption of nutrients. The intestine also releases mucus. This is to prevent the enzymes from attacking the intestinal mucosa.
Cells in the wall of the small intestine also produce hormones. For example, they stimulate the production of bile or pancreatic juice. Some hormones in the brain ensure that we feel full and do not keep on eating.
In the small intestine, the organism extracts most of the water from the food and thickens it. The water passes from the inside of the intestine into the blood. Through this dehydration, the intestine is also involved in the regulation of the water balance.
The intestinal muscles have the task of mixing the food pulp through rhythmic movements and transporting it bit by bit towards the large intestine.
The cecum is the first part of the large intestine and connects it to the small intestine. The appendix has the task of transporting the chyme further and preventing it from flowing back. There are also many lymphatic vessels there, which is why the appendix also serves as an organ of defense. It removes invading “pathogens”. The large intestine has various functions – an overview:
A very important function is to further remove water and salts from the liquid chyme and thicken it even more. The intestinal contents thus continue to solidify. At the same time, the large intestine adds mucus to the chyme so that it is more slippery and can be transported more easily.
The muscles of our large intestine perform wave-like movements. These ensure that the chyme reaches the anus bit by bit. “Intestinal peristalsis” is the medical term for this. When the undigested food has finally reached our rectum, the urge to defecate sets in: We feel the need to go to the toilet and empty our bowels. The undigested food then passes out as stool.
How often a person has a bowel movement varies greatly from person to person. Some empty their bowels once a day, some three times and some only a few times a week. The frequency depends mainly on how much fiber we take in with our food. A diet rich in fiber, for example from fruit, vegetables, whole grain products or legumes, promotes intestinal activity and supports intestinal health.
The large intestine also has the task of absorbing vitamins, for example folic acid and vitamin B12. Vitamins are generally indispensable for our body. The large intestine is also home to billions of bacteria. This intestinal microbiota also has various tasks. The bacteria live, for example, on those food components that are indigestible and unusable for us. Some bacteria produce important B vitamins such as biotin or folic acid as well as vitamin K (e.g. Escherichia coli, Lactobacillus acidophilus). An intact intestinal flora also keeps “harmful” bacteria in check. They cannot colonize properly, multiply excessively and spread. You should therefore pay particular attention to your intestinal health.
Like the small intestine, the large intestine is part of the immune system and is considered an important “immune organ”. The immune cells in the intestine are specialized in recognizing and fighting “pathogenic” bacteria. They are located in the connective tissue layer of the intestinal mucosa, communicate with each other via messenger substances and form antibodies. This information also reaches other immune centers in the human body via the blood and lymphatic system.
In addition, many nerve cells are localized in the intestinal wall. This means that your mental state can also influence your bowels. If you are often stressed or have a lot of anger, digestive problems such as abdominal pain, diarrhea or constipation can occur.
Various diseases and infections can develop in the intestine. Medical experts associate a disturbed microbiota with diseases such as inflammatory bowel diseases, allergies, diabetes, depression or neurological diseases such as dementia.
Diseases of the stomach and intestines can cause various and usually very unpleasant symptoms. Some examples: Flatulence (“bloated belly”), abdominal pain, abdominal cramps, nausea, vomiting, loss of appetite or diarrhea. Other symptoms such as fever, tiredness and fatigue may also occur. Read an overview of the most important intestinal diseases.
Intestinal infections, for example “stomach and intestinal flu”, are among the most common causes of intestinal complaints. The pathogens can be different and can be detected by a stool test, for example.
Common triggers of intestinal infections are:
You can become infected with intestinal pathogens in various ways, for example through spoiled food or through contact with infected people. You can become infected with the germs that cause the disease when you shake hands or touch infected objects, among other things. The symptoms can vary depending on the pathogen, for example abdominal pain, nausea, vomiting, diarrhea, loss of appetite or fever.
In appendicitis, it is not the appendix itself that is inflamed, but the appendix. The causes and development of appendicitis are still largely unclear. However, doctors suspect that pieces of feces in the appendix are responsible for the inflammation. The appendix narrows and becomes inflamed. Appendicitis often occurs in young adults and is considered a common disease. Many people wonder what they should do if they have appendicitis: Most people cannot avoid an operation.
Chronic inflammatory bowel diseases include Crohn’s disease and ulcerative colitis, for example. They belong to the so-called autoimmune diseases, in which the organism mistakenly attacks and destroys the body’s own structures – in this case the attack is directed against the intestine.
Both types of intestinal inflammation have many things in common, which is why they are not easy to distinguish. But there are also some differences. Ulcerative colitis, for example, usually only affects the large intestine and causes inflammation of the colon. Crohn’s disease, on the other hand, can affect the entire digestive tract. Intestinal inflammation can be accompanied by various symptoms, for example foul-smelling (“smelly”) flatulence.
What you can do about intestinal inflammation always depends on the cause. Chronic intestinal inflammation can be treated with various strategies, for example with medication or surgery. You can also do something yourself, for example through your diet. In addition, intestinal inflammation can be “fueled” by stress. Relaxation methods can be helpful here.
Colon polyps are benign growths of the intestinal mucosa in the colon. They are usually harmless, but over time they can develop into colon cancer (colon carcinoma). During acolonoscopy, a colon polyp can be detected and removed at the same time. Then bowel cancer can usually not develop at all. Early detection of bowel cancer is therefore particularly important! It is recommended for men and women in Switzerland from the age of 50.
Protrusions, so-called diverticula, can form in the intestine. These diverticula in the intestine do not protrude into the intestine, but protrude outwards. The protrusions usually form in the last part of the large intestine, the so-called sigmoid colon. This benign disease is called diverticulosis. However, the diverticula can become inflamed and lead to diverticulitis.
Irritable bowel syndrome is a functional intestinal disorder for which doctors cannot find an organic cause using “normal” examination methods. The disease is also known as irritable colon, irritable bowel syndrome or nervous bowel syndrome. Irritable bowel syndrome can vary in severity and can have a significant impact on the everyday life and quality of life of those affected. Women suffer more frequently from irritable bowel syndrome than men.
Coeliac disease is an autoimmune disease. The body reacts incorrectly to the normally harmless “gluten protein” gluten. This is contained in cereals and cereal products (e.g. from wheat, spelt, rye, barley). Coeliac disease usually affects the small intestine, but can also manifest itself in other organs.
The ingestion of gluten triggers inflammation in the intestinal mucosa, usually in the small intestine. The intestinal villi regress in this small bowel disease and the surface area of the small bowel is reduced. This means that the small intestine can no longer absorb enough nutrients. In the course of their illness, sufferers experience more or less severe nutrient deficiencies.
Short bowel syndrome can occur if part of the small intestine is missing after an operation. For example, people with Crohn’s disease sometimes require more extensive operations and the removal of sections of bowel. Sometimes a part of the intestine is missing in newborns and they suffer from short bowel syndrome from birth. The absorption and utilization of nutrients is restricted due to the missing section of the intestine. Those affected must adapt their diet to the reduced nutrient intake. You should seek medical nutritional advice.
Everyone has hemorrhoids. This is a vascular cushion with a good blood supply that surrounds the anal canal and closes it together with the muscles at the anus. In some people, however, the hemorrhoids are enlarged and cause various symptoms, such as bright red blood in the stool or itching. The main cause of hemorrhoids is constipation. Risk factors include a low-fiber diet, frequent and prolonged sitting, lack of exercise and genetic factors.
If the blood supply to the intestine is impaired, its blood supply is restricted. The cells then no longer receive enough blood and therefore oxygen and nutrients. The cause of an acute circulatory disorder can be a blood clot (thrombus), for example. A circulatory disorder can also be chronic. Angina abdominalis is the name of this clinical picture. Here the arteries in the intestine are calcified or narrowed and the intestine is no longer sufficiently supplied with blood.
An intestinal obstruction is life-threatening and always an emergency in which doctors must act quickly. With an intestinal obstruction, the transportation of food, fluids and digestive secretions is blocked. Sometimes transportation comes to a complete standstill. The reason for this is a blockage or obstruction in the intestine. Some examples: Scar tissue after a surgical procedure, tumors or hernias – this is where intestines, such as parts of the intestine, protrude through a gap in the abdominal wall.
The signs of an intestinal obstruction can be severe abdominal pain, nausea and constipation. Always seek medical help immediately if you notice such signs.
Colorectal cancer is a malignant tumor that develops in the colon (colon carcinoma) or rectum (rectal carcinoma). In medical terminology, this type of cancer is also called colorectal carcinoma or colorectal cancer. In the majority of cases (approx. 90 percent), bowel cancer develops from a benign bowel polyp. A healthy cell can degenerate and develop into a cancer cell. This process of transformation from “benign” to “malignant” can take up to ten years. This is why early detection of bowel cancer is so important.
A regular medical checkup is an important element of long-term health. With personalized preventive medicine, we determine your individual risk situation, offer sensible early detection examinations and show you exactly what you can do yourself to effectively prevent illness.