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Everything you need to know about bowel disorders

Everything you need to know about bowel disorders
Maintaining a healthy bowel is crucial to your body's health. Here are the facts about bowel disorders and what to do when things go wrong
Keeping your bowel healthy is really important for your overall health, as it is the main site in the body for the digestion and absorption of food and water. 

The small and large intestines

The bowel is the longest part of the digestive tract and consists of the small and large intestines, measuring around eight metres long. The first part of the bowel is the small intestine, which is about 6.5m long. All along the internal intestinal wall are finger-like extensions called villi, each about one millimetre long that increase the surface area of the intestinal wall. This aids the absorption of nutrients.
Intestines
The small intestine is divided into three parts: the duodenum, where it leaves the stomach; the jejunum, the middle section; and the ileum, which lead into the large intestine.
The large intestine comprises the colon and rectum. It is shorter, at around 1.5m, and wider than the small intestine, and does not contain villi. Its main function is to absorb water from digested food and turn it into faeces. It starts at a pouch called the caecum, from which the appendix protrudes.
It then rises up the right-hand side of the body (the ascending colon) and turns to cross the body (the transverse colon) just below the liver; finally, it runs down the left side (the descending colon) to terminate at the rectum and anus.

How the bowel works

When food enters the small intestine, it is broken down into its component chemicals by enzymes. Bile and pancreatic juices enter the top part of the duodenum through a duct. Other enzymes and mucus are produced by glands in the intestinal walls. The bowel also contains bacteria, which help to break down food as well as manufacturing some types of Vitamin B.
The breakdown products are absorbed into the bloodstream through the intestinal wall. The process is normally so effective that by the time the large intestine starts to fill, the contents consist only of liquid, fibre, some fat, vitamins and mineral salts, bacteria and waste products.
As part of the process of digestion, food is propelled through the bowel by an action known as peristalsis. The muscles in the intestinal walls automatically contract and relax in a rhythm—those in front of a portion of digestive material relax, while the ones behind it contract. The result is a rippling, wave-like motion that moves food through the system.
Peristalsis takes different forms in different parts of the bowel. In the small intestine, food is moved more slowly and in both directions, mixing it up and allowing more time for digestion. But the muscles of the large intestine contract only a few times a day, usually after meals. This forceful direct wave of contractions pushes waste products down to the rectum for expulsion during defecation.

Bowel habits 

It can take anything from 20 hours to more than 100 hours for food to pass through the digestive tract, and bowel habits vary from person to person. It is considered "normal" to evacuate your bowels anything from three times a day to three times a week. A doctor will describe an individual as constipated only if that person's bowel movements are hard, painful to pass or occur less frequently than every two days.
Bowel disorders
Taking laxatives to increase the frequency of your bowel movements is not advisable because their overuse may damage the intestines. But, if you suffer from persistent constipation, or if your usual bowel habits change and do not return to normal after several days, you should consult a doctor.

What can go wrong 

Problems can occur at any point along the bowel, affecting the absorption of nutrients and the expulsion of waste. The most common symptoms of bowel problems are difficulties with defecation, including constipation, diarrhoea and incontinence. There may also be wind, abnormal or bloody stools and abdominal pain.
A number of conditions involve a temporary inflammation of the intestinal wall, generally resulting from bacterial or viral infection. These include food poisoning, gastroenteritis, ileitis and proctitis.
  • Coeliac disease is an inflammatory condition arising as a result of damage to the small intestine caused by sensitivity to gluten. It adversely affects the absorption of nutrients by the intestines and is one of the main causes of malabsorption syndrome.
  • Crohn's disease is a chronic inflammatory disease that usually affects the ileum or the colon. It is also known, together with ulcerative colitis, as inflammatory bowel disease, in which the intestinal wall becomes thickened and ulcerated, sometimes causing an obstruction.
  • Diverticular disease is a condition in which pouch-like protrusions form in the intestinal wall. These may become infected, causing cramps and obstructing the bowel.
  • Obstruction. The bowel may become partially or completely blocked as a result of impaction of the faeces, or by distortion of the bowel's shape, as in a hernia, where a piece of bowel pushes out through the abdominal wall and becomes trapped. Inflammatory disorders may also cause an obstruction.
  • Irritable bowel syndrome, also called spastic or inactive colon, is one of the most common intestinal problems but is probably the least well understood. It affects about 30 per cent of British adults and 10 per cent have symptoms bad enough to require treatment. Women tend to seek medical attention for it more often than men, but it occurs equally often in both sexes. Irritable bowel syndrome is characterized by bouts of abdominal pain, with diarrhoea or constipation, excessive wind and a feeling that the bowels have not been emptied properly. The cause is not known, although attacks may be associated with stress.Treatments vary. Some people find that adopting a high-fibre diet is successful; others rely on antidiarrhoeal medicines or antispasmodic drugs; and others recommend psychotherapy or complementary techniques such as hypnosis.
  • Perforation. The intestinal wall can become perforated as a result of injury or damage caused by inflammation and ulceration. A perforated intestine is a medical emergency because the bacteria normally contained within the bowel are a source of infection. Prompt treatment is needed to prevent peritonitis, in which infection spreads throughout the abdominal cavity.
  • Ulcerative colitis is a chronic inflammatory condition that leads to ulcers forming on the colon and rectum. It is also popularly referred to as inflammatory bowel disease.
  • Polyps. Small growths called polyps can occur on the lining of the intestines. They are generally harmless, although in large numbers they can cause bleeding and diarrhoea. Suspected polyps should always be investigated, because some types can become cancerous.
  • Bowel cancer. The bowel may be affected by cancer. Tumours most commonly occur in the lower colon and rectum. Studies comparing different countries suggest that diet has an important part to play in cancer of the bowel. People in western countries who have low-fibre diets are particularly susceptible.People who notice a change in their bowel habits—such as constipation or diarrhoea, or the passage of blood, mucus or slime—that persists for more than 14 days are advised to seek medical advice. This applies particularly to people aged 35 or over. But in most cases the changes are likely to stem from a non-malignant bowel condition. Haemorrhoids, or, piles, for example, may cause rectal bleeding.Other symptoms of bowel cancer include abdominal pain, which may be a generalized ache or localized in the left lower abdomen with feelings of swelling. There may also be anaemia, loss of weight, loss of appetite and a general feeling of ill health.

When to consult a doctor

You should be alert to changes in your bowel movements, and consult a doctor in the following situations.
  • If you see blood in your stools.
  • If your stools are unusual—tarry, oily, greasy, pale, dark or offensive smelling.
  • If an unexplained bout of diarrhoea persists.
  • If constipation persists.
  • If there is an unexplained change in your bowel habits.
  • If you have any acute or persistent abdominal pain or cramps.
  • If you have severe wind.
  • If fever is associated with these symptoms.
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