Very few people like to talk about constipation as it is embarrassing. But there are few issues that cause as much mental and physical anguish as this disease. Irritation, sloppiness at work, tension headaches and absentmindedness .It gives rise to a plethora of symptoms. Constipation is defined as having less than 3 bowel movements per week. People who suffer from constipation frequently have to strain at stools and experience pain and a sense of bloating of the abdomen. Food as you know moves down the intestine with recurring waves of contraption called peristalsis, Though peristalsis is an automatic process requiring no stimulus its intensity is dependendent on how the intestine is stretched by food. . To understand what causes constipation we have to understand something of the ultra structure of the intestine and the physiology of nerve conduction and muscle contraction
From inside outwards the intestine consists of the mucus membrane, lamina propria, the muscularis mucosae, the submucus coat, the muscularis externa and the serous coat. The layers that are of interest to us in understanding constipation are the submucus coat and the muscularis externa. The submucus coat contains two bundles of nerve fibers arranged in two plexuses, the Messner’s plexus and the Aurebach’s plexus. These nerve fibers conduct electrochemical currents in the form of moving sodium and potassium ions. These impulses occur when the nerve fibers are stimulated by stretch receptor which as their name suggests are themselves stimulated by stretching of the intestine in whose walls they are situated. The muscularis externa contains two layers of smooth muscle cells. These smooth muscles contract when a nerve impulse initiated by stretching of the intestinal walls reaches its cell surface forcing calcium ions into the cytoplasm and making its contractile protein actin and myosin to interdigitate. The contraction of these muscle cells forces the stool stored in the intestine through the rectum to the exterior. In constipation the intestine is not stretched and these muscles do not contract. This is the basic patho-physiology of constipation.
There is another reason why constipation occurs and is that when stool moves through the colon, water is gradually absorbed from the faecal mass. If too much water is absorbed the stool becomes hard and is difficult to excrete.
Constipation is caused by these following causes
- Diets deficient in fibers.Fibers are present in fruits and vegetables. These are parts of the diet that cannot be digested and form a gel like paste with water increasing the bulk of the stool, stretching the wall of the intestine thus making the muscle cells contract, forcing the stool to the exterior. A high protein diet rich in cheese, eggs and meat contains few fibers and is more likely to cause constipation.
- Lack of liquids,iquids are important to relieve constipation as they increase the bulk of the stool besides making the consistency of the stool soft and easier to pass
- Lack of physical activity Physical inactivity is generally associated with constipation though the real reason is obscure. Elderly people or people recovering from illness or operations in hospitals are prey to this problem.
- Changes in life or routine Major changes in life processes like pregnancy may bring about constipation in women due to hormonal changes or due to the fact that the growing uterus compresses the intestine.
- Over reliance on laxatives Laxatives are available over the counter and many people use them regularly. Over use leads to dose tolerance and after some time even large doses of laxatives do not work.
- Ignoring the urge to have a bowel movement If someone ignores the urge for a bowel movement after some time the urge vanishes. This is because of the phenomenon of neuronal fatigue where the neurons stop discharging after repeated stimulation.
- Certain specific diseasesNeurological diseases like Parkinson’s disease, multiple sclerosis, pseudo obstruction, stroke and spinal injuries cause severe constipation followed by metabolic diseases such as diabetes,uremia,hypercalcemia and hypothyroidism.
- Colon and rectal problems Intestinal adhesions, obstruction, diverculosis, tumors, colorectal strictures, Hirschsprung disease and cancer all narrow the lumen of the intestine and rectum and cause constipation.
- Intestinal function problems intestinal functional problems that cause constipation are pelvic floor dysfunction, irritable bowel syndrome and anorectal dysfunction. In the latter disease inability to relax the pelvic muscles leads to constipation.
In conclusion it must be pointed out that all the causes of constipation are yet to be elucidated, The intestine contain a huge number of nerve cells labeled the enteric nervous system ,a completely new division of the nervous system whose functions are just being discovered. This holds out the brightest hope for the cure for constipation.