The Intestinal Phase – The Secondary Digestive Organs

The Small Intestine is broken down into three sections, the duodenum, jejenum and ileum.

In the first section, the duodenum, the bulk of chemical digestion (breakdown of food now called chyme) occurs, with the actual absorption (nutrients passing into the bloodstream for distribution) beginning in the jejenum.

However before all this begins, their requires the addition of several digestive secretions from the Pancreas & Gall Bladder, to make this happen.


When chyme is detected in the duodenum, two major hormones are released (cholecystokinin & secretin) that cause the pancreas to release digestive enzymes and bicarbonate, into the small intestine via the pancreatic duct.

The bicarbonate acts to raise the ph of the acidic chyme from the stomach, towards a mildly alkaline state, to allow the digestive enzymes to work properly. If this change in ph did not occur. then the chyme contents would pass through the digestive tract mostly unabsorbed.

Furthermore, the greater acidity of the chyme released from the stomach, ensures a more pronounced release of CCK & Secretin from the duodenum, which once more highlights the importance of stomach acid health.

The pancreas releases the following digestive enzymes to help in the breakdown of the chyme contents for absorption in the jejenum:

  • pancreatic amylase for carbohydrate

  • trypsin, chemotrypsin, elastase & carboxypeptidase for proteins

  • pancreatic lipase for fats

  • ribonuclease & deoxyribonuclease for nucleic acids.

What is interesting to note is that the exocrine (enzymes) actions of the pancreas make up 99% of its function, as opposed to its endocrine (hormones) cells, which may be surprising as most will associate the pancreas with the production of the blood sugar lowering hormone insulin. This goes to show how important optimum pancreatic function is to the process of digestion.

Indeed it is pertinent to mention that in 74% of diabetes patients, pancreatic exocrine insufficiency is reported, which may be from a diversion of pancreatic function away from its main exocrine purpose (digestion of food), towards more exaggerated endocrine fluctuations.

Gall Bladder

This organ is responsible for the storage and release of bile into the small intestine, which is vital to ensure the proper digestion of fats and fat soluble nutrients. Bile is produced in the liver and drains into the gall bladder to be stored until CCK is detected, and initiates its release into the small intestine.

Bile is crucial in fat absorption because it emulsifys the fat molecules, which basically involves breaking fat droplets apart to reduce the surface area, and allows the lipase (fat digesting) enzymes better access to do their work.

Emulsification of fat molecules is so important because fat and water do not readily mix, and as our bodies are mainly composed of water, this would be problematic.

If you have ever poured cooking oil into a sink full of water, you will notice how the fat separates from the water and forms an obvious film on the top of the sink. Without bile this would happen in the intestines, and fat digestion (including essential nutrients Omega 3, 6 & 9 fatty acids & Vitamins A, D, E & K) would be severely reduced.

Bile also carries detoxification metabolites, used hormones (e.g. oestrogen), cholesterol and red blood cell breakdown products (bilirubin), out of our bodies through the digestive tract.

So any impairment of bile flow from liver to gall bladder to intestines, would impact upon many systemic (e.g. cardiovascular, endocrine) functions and nearly every aspect of our general health.

Next Post: The Small Intestine

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