Things Yoram knows: the worm-shaped appendix

This week we were informed of the return of the Prime Minister's wife, Sara Netanyahu to her family after surgery to remove the appendix. Along with the sigh of relief, interest arises in Neta's question: why do you need the appendix if you take it out and you can live without it?

This week we were informed about The return of the Prime Minister's wife, Sara Netanyahu to her family after surgery to remove the appendix. Along with the sigh of relief, interest arises in Neta's question: why do you need the appendix if you take it out and you can live without it?

Of all the organs in the body, the appendix seems to be the most reviled. Even its anatomical name expresses contempt: Vermiform Appendix and in literal translation: the appendix shaped like a worm. Something strange happens on the lower right side of the stomach where the small intestine connects, whose job is to break down the food into its components and absorb them into the blood, to the large intestine, whose job is to squeeze the water out of the leftovers and send them to the toilet. At the junction, you find a fold of the large intestine that actually goes "down" and forms a pocket that has earned the unflattering name of the cecum. From this pocket also comes an extension that is 5-10 centimeters long and less than one centimeter thick - a coiled worm that does not attach anywhere: the appendix. This year it will be exactly 500 years since the discovery of the appendage by Berengario da Carpi - one of the pioneers of anatomy of the Renaissance period (in 1543 he was included In the seminal composition of Andreas Vesalius) and since then he is known to doctors only as a source of trouble. Inflammations in it were a common cause of death until the development of resection surgery at the end of the 19th century. If you can take it out and nothing happens, why is this worm crawling with us?

cellulose digestion

First of all, not everything in the body has a role. Our body is an archaeological museum of various remains of organs that were essential to our ancestors and today we would be fine without them. Shini understood They are the most painful example of this kind of residue. Apart from us and a few other monkeys, the appendix is ​​found in rabbits, a species of blind rat and in two marsupials: the opossum and the wombat. In rabbits, the cecum and appendix play an important role. There live the bacteria that break down the cellulose (cellulose) in the grass into digestible sugars for her. Accordingly, these parts of the intestine are large and store a considerable amount of food. Until recently, the caecum and even more so our appendix was considered a relic of ancient times of a diet based on field grasses. This is an accepted opinion even today and yet there are those who challenge this consensus.

The role of the appendix in other mammals

Since monkeys do not feed on grass, it is unlikely to expect the development of an appendix within this zoological series. The monkeys, or in their scientific name, the primates, in addition to humans, also include the apes (chimpanzees, gorillas and orangutans), "normal" monkeys and the proto-monkeys or the kippahs (known as the lemurs that adorn themselves with colorful tails). But anatomy refuses to listen to this logic. In the evolutionary transition between the "primitive" apes and the apes, there was actually an enlargement and development of the appendix. Rather embarrassingly, it turns out that the shape of the cecum and appendix in various monkeys was not known until the last decades. Biologists have excuses for this, since monkeys don't need a lot of abdominal surgery, the anatomy of their digestive system was learned from post-mortem surgeries and then the digestive tract tends to distort, the digestive juices break down the tissues and the muscles become lax. The food that remains in the system creates gas that swells the intestine so that it is not easy to learn from the corpse about the shape of the intestines in the monkey before it moved to the jungle which is all good. It was not until 1980 that work was published that was based on analyzes close enough to the time of death to allow a comparison between these parts of the intestine.

This diligent and bizarre work of collecting fresh corpses of monkeys and probing the stomachs yielded a surprise: the cecum and human appendix are similar to those of the gorilla but much larger and more distinct than those of the primitive monkeys. In some monkeys, such as the macaque, there is no appendix at all and in others there are small branches that require a lot of imagination to see in them something similar to our long worm. Accordingly, appendicitis is known only to us and to our first degree relatives such as chimpanzees and does not bother other monkeys. If we grew the appendix so long after we stopped eating grass, it's a bit hard to see it as a degenerate remnant and you have to recognize it as a full-fledged member of the group of digestive organs.

Not an evolutionary fossil

Well, if the appendix isn't an evolutionary fossil it should have an important enough role to justify the trouble it causes. The appendix contains tissues related to the immune system, but there is no immunodeficiency in all of us who flaunt a scar indicating its deficiency. A theory was recently published that seeks to explain the appendix puzzle. The intestinal bacteria do not just cruise around in the stomach, but form permanent and durable layers that adhere well to the lining of the intestine. Such layers of bacteria (Biofilm) living on mucus secreted by the host are very common in nature, there are plants that secrete no less than 20% of all organic matter they produce a sticky mucus that allows the growth of layers of beneficial bacteria around the roots. In a similar way, the coral also makes sure to adhere well to itself a layer of bacteria that it likes. Mucus secreting cells are scattered not only in the nose and trachea, in fact we produce most of the mucus in the stomach. There are bacteria that bind well to this runny nose and are also helped by special antibodies secreted from the intestinal wall to produce a layer that nicely coats the pipes. These bacteria are important to us both as aids in digestion and because harmful bacteria find it difficult to compete with the old layer of bacteria and bacteria that do not adhere to the intestinal walls will be excreted without causing damage.

But the gut is a turbulent place. When the infection develops, the reaction is diarrhea that sweeps out the good bacteria as well. This is where the appendix comes into the picture, it's good to have a calm bay from where the beneficial layer of bacteria will spread again when the storm passes. The role of the immune cells in the appendix, say the researchers, is not to fight bad bacteria but rather to help infect the good bacteria and help them create the necessary protective layer. And if the appendix is ​​so necessary, how do 6% of us manage without it? Our sterile living conditions in the modern world seem to render this defense mechanism redundant. The appendix was necessary for our ancestors who were much more exposed to infectious diseases of the intestine. This is also how the researchers answer the question of the "viability" of the appendix, which without surgery would cause death to so many people. The appendicitis itself, according to the theory, is the result of "excessive cleaning" that creates hidden unemployment in the immune system and causes the cells that were supposed to fight bacteria to produce work for themselves in the form of autoimmune diseases, allergies and, of course, appendicitis.

The removal of the appendix is ​​no longer a trivial operation, and it has long-term consequences

The removal of the appendix was considered a trivial operation until recently, but epidemiological studies from recent years indicate long-term consequences of this procedure. On the positive side, appendectomy reduces the chance of having ulcerative colitis and on the other hand, increases the chance of having another chronic intestinal disease - Crohn's disease. Those who do not have appendicitis are more sensitive to the attack of the bacterium Clostridioides difficile (Clostridioides difficile), a common infection among hospitalized patients after damage to the natural microbiome due to antibiotic treatments. Some studies point to a correlation between the absence of an appendix and diseases of the nervous system and in particular Parkinson's. In the tissue of the appendix, a high concentration of the protein alpha-synuclein is found, which is important for the function of nerve endings in abnormal folding (prion), which may explain the connection between the appendix and the nervous system. A statistical correlation was even found between removing the appendix at a young age and the chance of disability In depression, bipolar disorder or anxiety Decades later.

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More of the topic in Hayadan:

• Oops - the appendix has a role after all!
• About the randomness of evolution, the lack of planning and the flaws in the human body
• Five things that science knows for sure to be true