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Appendix Functions and Mysteries Plus Appendicitis Facts

Linda Crampton is an experienced teacher with a first-class honors degree in biology. She writes about the scientific basis of disease.

The appendix is a worm-like structure extending from the large intestine close to where it connects to the ileum.

The appendix is a worm-like structure extending from the large intestine close to where it connects to the ileum.

What Is the Appendix?

The appendix is a small, blind-ended tube that extends from a pouch called the cecum at the start of our large intestine. The lumen or cavity of the appendix is continuous with the lumen of the cecum. It has long been assumed that the appendix is a vestigial structure—one that had a function in our distant ancestors but no longer has a function in our bodies. Some researchers think that the appendix does have some useful functions, however.

The appendix can create big problems if it becomes inflamed and swollen due to an infection by bacteria. This condition is known as appendicitis. It's often a very painful disorder and is potentially dangerous. If the appendix ruptures, it may release its contents into the abdomen. This may result in peritonitis, a very serious condition in which the lining of the abdomen is inflamed. The usual treatment for appendicitis is to remove the appendix, but in special circumstances a doctor may use a different method.

The location of the appendix in relation to the rest of the human digestive system

The location of the appendix in relation to the rest of the human digestive system

Appearance and Location of the Appendix

The full name of the appendix is "vermiform appendix". Vermiform means worm-like, which is a good description for this organ. Its length varies considerably, but on average an adult appendix is 11 cm (4.3 inches) long and about 6 to 8 mm (0.24 to 0.32 inches) in diameter.

The colon is the first and longest part of our large intestine. It has three sections—the ascending colon, which is connected to the small intestine, the transverse colon, and the descending colon. The cecum is located at the start of the ascending colon and is found in the lower right area of the abdomen (from the owner's point of view). The appendix extends from the cecum near the ileum, which is the last part of the small intestine.

As far as we know, the cecum serves no special function in humans. In herbivorous animals, bacteria in the enlarged cecum break down the cellulose present in the cell walls of plants.

Not all mammals have an appendix, but some do. This adds to the mystery of its evolution and possible function. Mammals with an appendix include humans, great apes, wombats, opossums, and rabbits.

Although the appendix is located on the bottom right section of the abdomen, the pain of appendicitis may be diffuse at first.

Although the appendix is located on the bottom right section of the abdomen, the pain of appendicitis may be diffuse at first.

Some Possible Functions of the Appendix

The human appendix may have one or more functions. Some leading theories are listed below.

  • According to Loren G. Martin, a physiology professor at Oklahoma State University, endocrine cells (cells that produce hormones) appear in the appendix of a human fetus at about eleven weeks of development. The endocrine cells are active and release hormones. Hormones are chemical messengers and have specific effects in our bodies.
  • The lining of the appendix contains lymphoid tissue, which is part of our immune system. The immune system fights bacteria and other organisms that cause disease. We have lymphoid tissue in many other areas of the body in addition to the appendix.
  • Antigens (particles from invading organisms) may enter the appendix from the intestine and cause the cells in the lymphoid tissue to make antibodies. These antibodies may protect us when we are exposed to the antigens in the future. According to this theory, the appendix is acting as a training ground for the immune system.

The theories described above are interesting, but they need to be confirmed by more scientists. If they are true, we need to know whether they're insignificant because they are also performed by other parts of our body or if they are actually important.

Beneficial strains of Escherichia coli, or E.coli, live in our large intestine. According to one theory, the appendix is a safe house for helpful intestinal bacteria.

Beneficial strains of Escherichia coli, or E.coli, live in our large intestine. According to one theory, the appendix is a safe house for helpful intestinal bacteria.

Protecting Bacteria and Replacing a Ureter

It has been proposed that the appendix is a type of safe house for good bacteria that live in the large intestine. The suggestion was made in 2007 and in 2017 by researchers in different institutions. Intestinal bacteria are important for our health. According to the proposal, if bacteria in the large intestine are lost for some reason—such as in disease or due to antibiotic treatment—or if the intestine is invaded by bad bacteria that kill the good ones, the appendix "reboots" the large intestine. It does this by releasing good bacteria to recolonize the large intestine. Some scientists have criticized this idea, saying that although the appendix can send bacteria back into the intestine, it sends bad bacteria as well as good bacteria.

The appendix is occasionally used for surgical reconstruction of damaged structures in the body, such as a ureter (the tube that transport urine out of the kidney to the urinary bladder) in young children. This is not a natural function of the appendix, but it's certainly useful.

Possible Causes of Appendicitis

The word appendicitis mean "inflammation of the appendix". It's not always clear why this inflammation develops. The problem may begin when the opening to the appendix is blocked by mucus produced inside the appendix or by feces moving through the colon. The feces may become hard, forming a fecal stone that traps bacteria inside the appendix.

Trapped bacteria reproduce and their population increases, since they can't escape into the colon. The bacteria trigger the inflammatory response, which is the body's way of fighting infection and damage to the body. Pus and fluid build up during this response, causing the appendix to swell and become painful.

The appendix may also become blocked when its lymphoid tissue swells due to a gastrointestinal infection or an infection somewhere else in the body. In addition, the entrance to the appendix may be blocked by an abnormal growth of tissue. Rarely, appendicitis develops because of trauma to the abdomen.

Possible Symptoms of the Disorder

The most noticeable symptom of appendicitis is generally pain.

  • The first symptom of the problem is usually a dull pain near the naval. The pain is often diffuse and isn't localized in any one area.
  • This pain gradually moves to the lower right quadrant of the abdomen and becomes more severe.
  • Pain become worse as time passes.
  • Pain is felt when the lower right abdomen is pressed. (This should always be done very gently and with shallow pressure.)
  • Pain is felt when the hand that was pressing the abdomen is released (rebound tenderness).
  • Pain is worse when a person coughs, walks, or moves.

These symptoms may be caused by other conditions besides appendicitis. A doctor must be consulted for a diagnosis.

Other Possible Symptoms

Other possible symptoms of appendicitis include the following:

  • nausea and vomiting
  • loss of appetite
  • abdominal swelling
  • fever
  • diarrhea or constipation
  • inability to pass gas

The symptoms of appendicitis are shared with other disorders, so a doctor will often perform diagnostic tests before the appendix is removed.

An Appendicitis Poll

The appendix population of neutrophils (a type of white blood cell) increases significantly during appendicitis. The lobed structure in these stained neutrophils is the nucleus.

The appendix population of neutrophils (a type of white blood cell) increases significantly during appendicitis. The lobed structure in these stained neutrophils is the nucleus.

Removal of the Appendix

A person with appendicitis shouldn't refuse to get their appendix removed if this is recommended by a doctor. They will probably be in too much pain to consider refusing the surgery, anyway. It's probably not a good idea to remove a healthy appendix, however, even though a person can live an apparently normal life without it. The organ may have hidden benefits.

It used to be a common procedure to remove the appendix during abdominal surgery for another problem. This was believed to be a wise move, since it was thought that we didn't need the appendix and its removal would prevent the development of appendicitis in the future. Removing the organ when it's healthy is no longer a routine procedure.

People with severe lower abdominal pain need to get a prompt medical examination. An appendectomy or appendicectomy (surgery to remove the appendix) is usually straight forward and the patient generally recovers quickly. If an infected appendix ruptures, pus and fluid may collect near the appendix. Doctors may be able to drain this fluid from the body. If pus inflames the membrane lining the abdomen, which is called the peritoneum, doctors have to use aggressive treatment to cure the infection. Peritonitis may be life threatening.

Appendicitis is most common in people between the ages of ten and thirty but can occur at any age.

Antibiotic Treatment in Specific Situations

In some cases of uncomplicated appendicitis (cases in which the appendix hasn't ruptured), antibiotics have cured the infection and surgery hasn't been necessary. A delay in surgery while antibiotics are tried worries some doctors, however. They are afraid that if the antibiotics don't work the appendix could continue to swell and eventually rupture.

In some people who are weakened by another illness, surgery may be risky. Doctors sometimes try antibiotics as a first approach to treating appendicitis in these people. It's very important that anyone who receives antibiotic treatment for an inflamed appendix is monitored closely by their doctor. There seems to be a 10% to 20% risk of recurrence of appendicitis after apparently successful antibiotic treatment.

In this article, the word "appendicitis" refers to an acute condition which appears quickly and has dramatic symptoms. There is another, much rarer form of the disorder known as chronic appendicitis. This is a long-lasting condition with milder symptoms. Antibiotics are most likely to be tried as a treatment for this type of appendicitis.

Although there is no proven way to prevent appendicitis, eating green vegetables may reduce the risk.

Although there is no proven way to prevent appendicitis, eating green vegetables may reduce the risk.

Can Appendicitis Be Prevented?

There is no known way to prevent appendicitis, although eating a diet that is high in fibre may reduce the risk. Fibre is found in foods from plants, so eating lots of grains, legumes (also known as pulses), vegetables, and fruit would create a high fibre diet.

In 1986, researchers explored the link between acute appendicitis and diet in 59 areas of Britain. They found a positive correlation between potatoes and appendicitis but a negative one between green vegetables and appendicitis. This is an old study and really needs to be repeated. Since green vegetables are known to have many health benefits besides possibly reducing the risk of appendicitis, however, it's a good idea to include lots of them in the diet. Potatoes can be a good food as well, depending on how they are prepared, but the regular consumption of green vegetables is important.

An Interesting Organ

The appendix and its functions (or potential functions) are very interesting. I'm hoping that scientists soon make more discoveries related to the organ. Mysteries about the human body still exist. Many of the processes that occur inside it are both fascinating and complex.

For many of us, the pancreas never causes problems. It might even be helping us. When a problem with the organ does occur, it's generally very noticeable. Fortunately, an effective treatment is available. It’s important to see a doctor to get the condition diagnosed correctly and treated quickly.


  • Possible functions of the appendix from Scientific American
  • The appendix may have an important function from the Medical Xpress news service
  • The appendix may be a safe house for bacteria from Time magazine
  • Antibiotics and appendicitis: University of Nottingham Report from WebMD
  • Antibiotics could sometimes replace surgery for appendicitis, research suggests, from the Science Daily news service
  • Vegetable Consumption and the Risk of Acute Appendicitis from the NIH (National Institutes of Health)

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

Questions & Answers

Question: What is a high neutrophil level?

Answer: Neutrophils are a vital category of white blood cells. They are part of our innate immune system and help our body to fight infections. You would need to ask your doctor about whether you have a high neutrophil level and about what the significance or effects of this high level might be if it exists.

© 2013 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on January 01, 2019:

Your son’s efforts sound very worthwhile.

DW Davis from Eastern NC on January 01, 2019:

One positive side effect was that the incident encouraged him towards medical research and now he's a Graduate Researcher at NC State working on better ways to repair orthopedic injuries and wounds.

Linda Crampton (author) from British Columbia, Canada on December 31, 2018:

What a scary and interesting story. I’m very glad that it had a happy ending.

DW Davis from Eastern NC on December 31, 2018:

We nearly lost our youngest son to a ruptured appendix when he had just turned 18 and was in his senior year of high school. He'd been complaining of a minor stomach ache for a couple of days but continued to take part in all his normal activities including track practice and Cotillion. When we went to the doctor, the doctor suspected appendicitis and tests confirmed this. The surgeon discovered his appendix had ruptured and what saved him, besides our son's own excellent physical shape and health, was a cyst that had formed around the appendix.

Our son's first official legal paperwork as an 18-year-old adult was to sign the consent form for his surgery. This all happened nearly 5 years ago and he had a full recovery.

Linda Crampton (author) from British Columbia, Canada on November 16, 2017:

I've only known one person who experienced appendicitis, or at least only one person who told me about it. He was a student of mine and still in high school. I'm glad that both he and your friend got medical attention.

FlourishAnyway from USA on November 16, 2017:

I had a friend who had appendicitis and had her appendix removed. She had always been a heavy girl but lost a lot of weight for some reason afterwards.

Linda Crampton (author) from British Columbia, Canada on September 03, 2014:

I appreciate the comment, the vote and the pin, Pamela. Thank you very much!

Pamela Dapples from Arizona. on September 03, 2014:

Very useful and interesting hub -- and well-organized. Voting way up and pinning.

Linda Crampton (author) from British Columbia, Canada on April 26, 2013:

Hi, Peg. Thanks for the comment! I appreciate your visit. I'm glad that your appendicitis was treated successfully.

Peg Cole from North Dallas, Texas on April 26, 2013:

Hello AliciaC, This was quite interesting and informative, more so because I had appendicitis a couple of years ago. I found out at that time that it mostly occurs to much (much) younger people. Your explanation of what it is and how treatment is administered was fascinating. The surgery today differs quite a bit from that of years ago. Great illustrations, too.

Linda Crampton (author) from British Columbia, Canada on February 16, 2013:

What a horrible situation, Phoebe. I'm so glad that I haven't had appendicitis! Thanks for sharing your experience.

Phoebe Pike on February 16, 2013:

When I had it, I was vomiting nonstop and had extreme pain and hot chills. It was torture. They removed it right before it burst. I was 8-year-old at the time and I still remember it like it was yesterday.

Linda Crampton (author) from British Columbia, Canada on February 05, 2013:

Thank you very much, Vicki. I've never had appendicitis either, although I've known people who have. I've always been very glad that it's passed me by!

Vickiw on February 05, 2013:

Alicia, this is a very detailed and informative Hub, congratulations on your interpretation of the information. I have never had appendicitis either, but it is definitely a problem I would not like to have.

Linda Crampton (author) from British Columbia, Canada on February 05, 2013:

Thank you very much for the comment and the vote, drbj. It will be interesting to find out what the function or functions of the appendix actually are and to discover how significant these functions are.

drbj and sherry from south Florida on February 05, 2013:

Fascinating information in depth about the appendix, Alicia. I was amused by your description of that worm-like-looking appendage as a kind of 'safe house' within the body. Mebbe so! Voted up, of course.

Linda Crampton (author) from British Columbia, Canada on February 05, 2013:

I'm glad that you've been so healthy, Bill, and I hope that you continue to be problem-free! Thanks for the comment.

Bill Holland from Olympia, WA on February 05, 2013:

I've never had trouble with my appendix, but then I never have trouble with any of my parts. My time is coming but I'm enjoying the peace and health while it lasts. Good information, Alicia.

Linda Crampton (author) from British Columbia, Canada on February 05, 2013:

Hi, FullOfLoveSites. Thank you very much for the comment and the votes. It's thought that when our ancestors relied on plants for food the appendix was bigger. It has a strange appearance today!

FullOfLoveSites from United States on February 05, 2013:

I have heard something like in the olden days man ate raw foods and roughage foods and the appendix played a great function in breaking them down. Now the appendix's use has been limited because we eat more processed foods. Very informative hub.

Up and useful. :)