
The Large Intestine
It's very important that UCers understand where the large colon is and how it works. I've found that being more knowledgable about it has led to: a better understanding of which type of colitis I have; more precise explanations for Doctors; a better awareness of what area is effected by treatments, diet changes etc.; an increased awareness of what might happen e.g. how long before a bowel movement if there is a cramp somewhere along the large intestine.
Large Intestine Sections
The Ascending ColonThis is the section of the large colon that's on the right side of the abdomen. I've read questions by UCers asking whether the pains they were getting on the right were anything to do with colitis - this shows that they can be. It's also worth noting if symptoms are at the top or bottom of the Ascending colon as well; you can really start pinpointing which areas might be inflammed with this knowledge. Pancolitis affects this area and may also effect other parts of the large colon. |
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The Transverse ColonThis is the section of the large colon that crosses the abdomen. Because of its location, aches and pains in this part of the colon are often mistaken for the stomach which actually sits just above. When the transverse colon is inflammed, the location of aches and pains tend to occur across the bottom of and/or just underneath the rib cage. Pancolitis affects this area and may also effect other parts of the large colon. |
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The Descending ColonThe Descending colon is located down the left side of the abdomen. When the Descending colon is inflammed, the location of the aches and pains tend to occur down the left side of the abdomen. Left-sided colitis affects this area only. |
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The Sigmoid ColonThe Sigmoid colon is located more or less along the bottom left side of the abdomen. When the Sigmoid colon is inflammed, the location of the aches and pains tend to occur next to or below the belly button. Proctosigmoiditis affects this area only. |
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The RectumThe Rectum is located in the centre, below the abdomen and further back. When the Sigmoid Rectum is inflammed, the location of the aches and pains can feel like they are below the belly button and/or also at the back of the body, nearer the exit. Inflammation in this area also causes the worst cases of urgency due to the close proximity to the exit. Proctitis affects this area only. |
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How the Colon WorksThe large intestine is basically a hollow tube with muscles along it to move waste, although the tube actually has many layers. It doesn't produce any digestive enzymes, and the pH is 5.5 to 7.0, which is slightly acidic.
The main function of the large colon is to absorb any remaining nutrients and water from the waste before removing it. It absorbs electrolytes (mainly sodium & potassium) and vitamins (K and B7) which are produced by bacteria in the large colon. Vitamin K is particularly important because the amount taken daily from food is generally not enough for blood coagulation (clotting). When considering the ulceration caused by colitis, it seems obvious then, that a lack of vitmain K will go hand in hand with the disease. The fact that vitamin K helps our blood to clot could be part of the reason that UCers experience blood. In a healthy person about 10% of the water and vitamins used by the body are absorbed through the colon. However, When dietary intake is too low, vitamins used by the body which are absorbed through the large colon contribute significantly. Colitis sufferers often have a limited dietary intake and are also unable to absorb vitamins from the colon due to inflammation - this can cause problems such as diarrhea, dehydration and a deficiency in some vitamins and minerals. Studies have shown that sufferers of Ulcerative Colitis and Crohn's disease absorb less sodium and water and secrete more potassium. Also, with distal colitis the permeability of the rectosigmoid (rectum and sigmoid) colon is reduced, which gives an insight into the mechanism of diarhhea. To compound things further, if people with a limited dietary intake are given antibiotics, the helpful bacteria that produce vitamins can be destroyed, resulting in further deficiencies. The colon contains over 700 species of 'friendly' bacteria some of which aid digestion or produce fat soluble vitamins. There are estimated to be over 100 trillion microbes in the gut, which means humans are made up of many more microbes than genes, and it's why the gut microbiome is an interesting area of research. |
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Haustra (Segments) - Peristalsis (waves) The colon appears to have lots of segments along it, these are collectively called haustra. A single haustrum is a small pouch which slowly contracts approximately every 25 minutes. The effect is that of a slow wave which moves the contents along to the next pouch and so on. Loss of the haustra is a sign of chronic ulcerative colitis. These involuntary waves (they happen without us thinking about it) are known as peristalsis (I prefer to call it flexing!!). The waves can be the reason behind painful cramps that UCers experience. Small waves occur throughout the day, large waves occur en masse 1 to 3 times per day, propelling waste from the large colon to the rectum. |
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