BABY AND CHILDHOOD DIGESTIVE SYSTEM DISORDERS: HOW THE DIGESTIVE SYSTEM WORKS

Friday, May 8, 2009 8:31

Have you ever wondered how your tummy system works? When you poke something into your mouth it vanishes. We all know that. But vanish where, and what happens to it?

As you probably know, the bowel, or intestinal, system really begins at the mouth. From the mouth is a continuous canal to the far end, to an opening we call the anus. It is actually a single tube which we arbitrarily divide into segments and call by different names.

The oral cavity is guarded by gums and teeth in front, and the tongue sits in the lower part. A baby is born with gums but no teeth in sight. That’s fortunate for the breast-feeding mum. Have you ever thought how terrible it would be breast-feeding a baby with the full component of twenty sharp milk teeth? Ouch! No, several months pass before the baby is endowed with a first set of teeth.

The oral cavity leads directly into the pharynx, passing the two red tonsils on each side, and the pharynx gives way to the oesophagus, or food pipe. This leads to the stomach via a small valve.

Digestion starts when food mixes with saliva in the mouth. But in the stomach it receives a major boost—the wall is lined with many glands which pump potent acid and some other digestive chemicals, called enzymes, into the mass of food. It tends to become a mixed-up mass, largely fluid in nature.

The stomach is merely a dilated part of the bowel. It houses the food until the valve at the far end allows it to pass into the next part, called the duodenum.

At regular intervals, the stomach valve (called the pyloric valve) opens and the fluid starts its long trek down the bowel. Firstly it traverses the duodenum, which then leads into the small bowel (firstly named the jejunum, and later the ileum) Here various extra enzymes are added, and much of the nutritional elements of the food is absorbed by the bowel wall for use in the body.

At the far end of the small bowel (named ’small’ not because of its length, for it is very long, but because it is narrow in diameter), it dilates into an area called the caecum. This is where the small bowel connects to the large bowel (‘large’ because it is very wide in diameter, although it is quite short in length, in contrast).

Here the appendix occurs as a small worm-like organ (about the thickness of a pencil). It has an opening where it joins the caecum. It is several centimetres long and has a blind, closed far end; if its opening, or mouth, becomes blocked then trouble looms, for germs can easily establish a foothold and set up an acute infection which we refer to as acute appendicitis.

In the large bowel, fluid (mostly water) is reabsorbed by the walls, making the contents much firmer. From the large bowel, the canal continues as the rectum. There, in the rectum, the residue of the bowel contents is stored until a suitable time when it can be passed. When this occurs, it gently passes down a much narrower tube, called the anal canal.

At the end of this is a valve, called the anal sphincter. When this releases, the final, unwanted debris is expelled from the digestive system via an aperture called the anus. Afterwards, the valve re-closes, and stays closed until another bowel movement is made.

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