We are reaching the end of our journey through the labyrinth that is our digestive system. Today the intestines, but also a couple of glands that are essential to the process itself. I hope you have enjoyed the trip and if you were new to the scenery, found it useful.
The small intestine
The small intestine is made up of three parts, the duodenum at the entrance, the jejunum and the ileum.
The duodenum is joined to the stomach and receives the highly acidic mix that has now been produced by the gastric juices. There is a danger that the duodenum would be eaten away by this acid so it secretes a thick mucus to protect itself. Within the layers of the duodenum are also glands that produce an alkaline juice to neutralise the acid and provide the enzymes to continue the digestive process. Because of the corrosive effect of the hydrochloric acid in the food at this point the cells in the mucus membrane replicate faster than anywhere else in the body. At this point bile and pancreatic juices join the mix and the food moves about 10 inches down into the jejunum where nutrients are absorbed into the blood stream before the remaining liquid is passed into the ileum and then onto the colon for excretion.
The pancreas is one of the largest glands in the body and its main role is the secretion of hormones including insulin (when there are raised sugar levels in the blood), glucagon (when there is lower sugar levels in the blood) which maintains a normal balance. Also pancreatic juices, which are vital for effective digestion.
It lies across the top of the abdomen, below the liver and tucked into the duodenum section of the small intestine.
The pancreas is made up of cells (acinar cells) that secrete into small ducts that connect together until they feed pancreatic juices into a main duct running through the centre of the gland which feeds directly into the duodenum. The pancreatic juice contains not only the enzymes needed to breakdown carbohydrates, proteins and fats but also sodium bicarbonate to help neutralise the acid.
Within the acinar cells are Alpha and Beta cells that produce insulin and glucagon respectively. These are taken from the pancreas via the Mesenteric vein into the blood stream where they will balance blood sugar levels.
The gallbladder is a small pear shaped muscular structure on the underside of the liver on the right of the abdomen. It is attached to the common bile duct, which connects the liver to the duodenum, by the sphincter of Oddi. Excess bile leaves the bile duct at the cystic duct and is then stored and concentrated in the gallbladder until needed. Bile is used in the digestion of fats as they pass through the duodenum and is then either excreted or absorbed back into the bloodstream.
By the time the digested food (chyme) has reached the colon all the nutrients should have been absorbed leaving a mixture of insoluble fibre and assorted waste products from the body’s operating systems mixed with water.
The Colon is the last part of the 30 foot alimentary canal and is used to remove excess water and solidify waste products before they are excreted from the body. It is a muscular tube, which moves the waste in a series of movements similar in nature to a washing machine and piping bag. The contents are churned and then moved on mass by contractions whilst excess water is re absorbed into the body. As the faecal matter loses water it becomes more solid so the lining of the colon secretes mucous to ease its passage through to the rectum.
There is still a digestive role for the colon to play, as it is at this point that billions of bacteria in the colon synthesise the essential vitamins K as well as gases such as hydrogen, carbon dioxide and methane. Some of which make themselves more evident when we have consumed high fibre foods like beans.
From start to finish a normal and healthy digestive system will process the food you eat in approximately 12 to 24 hours. The longest period of digestion is in the colon where the process may take several days. Obviously what we eat will affect the timing of the process as harmful bacteria in food can cause the body to rush the elimination resulting in diarrhoea or the lack of fibre may result in constipation.
Ideally you should be eliminating food every 12 hours but certainly every 24 hours. As you will have seen there are many organs and processes involved and if only one of these is out of sync with the rest of the digestive system it can have a knock on affect that could potentially damage your overall health.
Eating a balanced diet is the best way to maintain a healthy digestive tract and so is some simple maintenance from time to time including dental care and detox programmes.
©Sally Georgina Cronin – Just Food For Health 1998 – 2017
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