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Archive for June, 2009

So,  we’ve covered the movement of food/nutrients from the “brain” (as we initially think and perceive the meal we’re about to ingest), into the mouth, down the esophagus and into the stomach, where the first major digestive processes take place.  If our digestive system is healthy, and our liver, gallbladder, pancreas and other supporting organs are functioning optimally, the Chyme, created in the stomach, is now ready to move into the part of the body specifically designed to transfer the nutrients through the blood stream into every cell in our body.   The next part of the journey reminds me a bit of the old 1930’s jazz song by Louis Armstrong, and others: 

The music goes ’round and around
Whoa-ho-ho-ho-ho-ho
And it comes out here

Are you ready for some intestines? 

The small intestines are about 25 feet in length and if spread out, would cover an entire tennis court.  They are made up of the duodenum, the jejunem and the ileum, each having important and distinctive functions. intestine

 

 The duodenum is largely responsible for the breakdown of food in the small intestine, using enzymes from the pancreas.   As the Chyme enters the duodenum, it is also responsible for regulating the rate of emptying the stomach with the help of two major digestive hormones. Secretin and cholecystokinin (or CCK) are released from cells in the duodenal lining as a result of the high acidity and the fats present when the pyloric sphincter or valve (between the stomach and duodenum) opens and releases gastric Chyme for further digestion. These cause the liver and gall bladder to release bile, and the pancreas to release bicarbonate and digestive enzymes such as trypsin, lipase and amylase into the duodenum as they are needed.

The first two parts of the small intestine, the duodenum and jejunum are responsible for most digestion and assimilation, with continued assimilation in the ileum.  These first two sections of the small intestine are completely lined with small finger like projections called villi , where most absorption takes place. If you looked inside the upper intestines, the surface area would look much like a terry-cloth towel, which greatly increases the surface area for optimal absorption (yeh, just like a towel).  Each villus contains a network of capillaries in which the broken-down food particles are absorbed and carried into the blood stream.

Once again, muscular contractions move the Chyme along. Whenever a section of the small intestine becomes stretched, peristalsis (waves of contractions) occurs at spaced intervals. This not only moves the Chyme along but also mixes it with digestive secretions. At the end of the small intestine is the ileocecal valve (another valve separating parts of the digestive system so that material doesn’t easily move the wrong way).   As with the connection between the stomach and the small intestine, various hormones and feedback mechanisms regulate the passage of Chyme through the ileocecal valve into the large intestine. When the ileum becomes stretched and full, the valve opens to allow the passage of Chyme and if the large intestine is too full, the valve remains closed until the bowel empties.

The small intestine meets the large intestine at a sharp right angle bend. To the left is the cecum, a kind of holding tank, and to the right the bowel. Attached to the cecum is the appendix, once considered a non-functioning or “vestigial” organ but now recognized as serving an important immunological function. The appendix contains a high concentration of lymphoid follicles that produce antibodies to help keep the bacteria of the colon from infecting other areas of the body, such as the small intestine and the bloodstream, particularly in early life.

The large intestine or colon is five to six feet long with a diameter of about two inches and is divided by sharp turns into three major parts–the ascending colon on the right hand side of the body, the transverse colon which runs from right to left across the upper abdomen, and the descending colon which carries the mass of digested food downward to the rectum. The purpose of the large intestine is threefold: storage of waste materials and undigested food from the small intestine–not just the breakdown products of what we take in but the residue of secretions, sloughed-off cells and dead bacteria that accumulate during the digestive process; the absorption of water and electrolytes from the food residue; and the further decomposition of solid materials by the action of millions of bacteria. Combined contractions of circular and lengthwise muscles surrounding the colon roll over the fecal materials to ensure that all of it is exposed to the intestinal wall, so that all the fluid can be absorbed. Special cells, called goblet cells lining the large intestine, secrete mucus that protects the walls of the intestine, help maintain alkalinity and provide a medium to hold the fecal matter together.

The final stage of this incredible journey is the movement of the now solid fecal matter from the transverse colon via strong contractions down the descending colon and into the rectum, a process that occurs only a few times each day–usually upon arising in the morning or immediately after breakfast. When these movements force a mass of fecal matter into the rectum, the desire to evacuate is felt.

So, why so much time and space on digestion?  Because it is so critical to almost everything else that goes on in the body.  I’ll be referring back to this information to describe various healthy and dysfunctional conditions, and how they can be supported for continued or improved health and well-being.  Next time, we’ll look at some of the problems that occur with the digestive system that plague millions of people throughout the world, especially in westernized countries,  that can be helped with improved nutrition.

Thanks to Sally Fallon and the Weston A. Price Foundation for parts of the above description
www.westonaprice.org

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