THE DIGESTIVE SYSTEM

THE DIGESTIVE SYSTEM

Food is vital for life. It is needed to fuel the chemical reactions which occur in every cell. For the synthesis of new enzymes, cell structures, bone, blood and all of the components of the body, and for the release of energy, needed for these building processes. Remember that life takes place at the cellular level. Every one of the tiny cells in our body is a factory, performing all of the different functions that go together to collectively make up our body, and these 'factories' require fuel.

Our food is simply 'too large' to enter the cells. The process of 'breaking down' this food into tiny molecules which are capable of entering the cell is called digestion, and all of the organs which collectively perform this function are known as the digestive system.

The Alimentary Canal

The Alimentary Canal or Gastro Intestinal Tract (GI), refers to the entire length of the tube which runs from our mouth to our rectum. The Digestive System includes the alimentary canal, plus the associated structures of the salivary glands, teeth, liver and gall bladder and the pancreas. These structures provide the function of chewing and churning the food, which is the process of mechanical digestion, and the secretions for the chemical digestion of our food.

The Mouth or Bucal Cavity, is the first structure of the Alimentary Canal. It contains 32 adult teeth. Food is chewed to break it down into smaller particles and to expose the greatest area for the digestive juices. Saliva is secreted by many small glands in the mouth and also by the Salivary glands, known as the Parotid glands, the Submandibular glands and the Sublingual glands. Normally, just enough saliva is secreted to keep the mucous membranes of the mouth moist, but when food enters, the amount of saliva increases. Its function is then to lubricate, dissolve and begin the chemical breakdown of food.

The smell, sight, sound or touch of food stimulates saliva production. Saliva is mainly water, plus amylase and mucin. Amylase digests carbohydrates in the mouth. Mucin, in combination with water, provides mucous, necessary for lubrication.

The tongue contains the taste buds and is instrumental in the swallowing reflex. Food is chewed and formed into a bolus, which is then swallowed. Swallowing is a voluntary action, but once initiated, it becomes involuntary.

The Oesophagus is the tube which carries the food to the stomach. Mucous is also produced in the epithelial lining of the oesophagus, and the food is transported to the stomach under the action of Peristaltic waves. Peristalsis, is an expanding and contracting wave‑like action which moves food along with each contraction. Peristalsis is the means of moving food through the entire length of the GI. It is this action that allows us to swallow food when upside down. The food then passes through the Gastro‑oesophageal sphincter, and into the stomach. A Sphincter, is a circular band of muscle which acts to constrict an orifice. There are a number of sphincters located along the GI.

In the stomach, the food is churned by the Peristaltic movement of this organ which further exposes it to the gastric juices. Salivary amylase is neutralised by the stomach acids. Gastric juice consists primarily of Hydrochloric acid, the enzyme Pepsin, and Intrinsic factor. These are all produced by the secreting cells of the Gastric Mucosa (stomach lining).

The principal chemical digestion which takes place in the stomach is that of protein, under the action of the enzyme Pepsin. Pepsin works best in an acid environment, which is created by the presence of the hydrochloric acid. The mucous secreted by the gastric mucosa is slightly alkaline and this protects the stomach lining from being digested by this strong acid. The stomach empties all of its contents into the duodenum via the pyloric sphincter, between 2 and 6 hours after ingestion. Carbohydrate rich foods leave the stomach after a few hours. Protein foods are slower, and emptying is slowest after a meal containing large amounts of fat.

What leaves the stomach is partially digested protein. Little absorption takes place in the stomach. Only the smallest molecules like water, alcohol, caffeine and salicylic acid are absorbed here. These last three will contribute to the formation of stomach ulcers (peptic ulcers) and must be removed from the diet of anyone who suffers with this complaint. Hyposecretion of the protecting mucous will also allow stomach acid to burn the wall of the stomach, and may result in an ulcer. Stress, is always implicated in Gastric ulcers. More on ulcers later.

Intrinsic factor is necessary for the absorption of vitamin B12. A lack of intrinsic factor will result in mal absorption of this nutrient with pernicious anaemia being the likely outcome. More on anaemia later.

At this point it is important to mention certain 'feed back' loops which govern digestive secretions. Firstly, sufficient stomach acid is critical if we are to digest protein efficiently in the stomach. The sight and smell of food stimulates gastric secretions. Similarly, food of any kind in the stomach causes distension and this stimulates receptors in the stomach lining (gastric mucosa) which further initiates the flow of gastric juice.

A number of hormones are released as the chyme moves from the stomach into the intestines. The two principal hormones are Secretin and Cholecystokinin. Their production is stimulated by stomach acid and their effect is to firstly inhibit further gastric secretions and secondly to stimulate bile flow from the liver, and enzymes from the pancreas and intestinal mucosa.

The purpose of this information is not to boggle you with complicated details but to illustrate the importance of digestive secretions of all types and to demonstrate the interdependency of each upon the other. The importance of digestion in maintaining 'good health' cannot be overstated. A lack of HCI in the stomach will not only effect protein digestion but will also inhibit the production of digestive secretions from all organs further down the line.

Approximately 90% of people over the age of 50 years suffer Hypochlorhydria (under production of stomach acid) or Achlorhydria (absence of stomach acid). This is primarily a degenerative condition resulting from advancing age and severely aggravated by stress and dietary abuses.

The cells of the gastric mucosa (stomach lining) are highly 'nutrient dependent'. That is, they must be kept 'well fed' if they are to produce their digestive secretions. Possibly their most important nutritional requirement would be for vitamin 'B' complex.

Chyme, is the result of the stomach's digestive processes and is a semi‑fluid mixture of food and gastric juices. Gastric emptying is effected by increasing peristaltic waves in the stomach, and is much dependent upon the quantity of chyme and its composition. Fats slow this process, as do psychological factors.

Vomiting is an involuntary action responsible for removing anything that may be harmful to the stomach, or in excess of bodily needs.

The Small Intestine is about 20 feet in length and consists of 3 sections, the Duodenum, the Jejunum, and the Ilium. Chyme passes from the stomach, through the pyloric sphincter into the duodenum. The duodenum is only about 6 inches in length and it is here that the small intestine receives the pancreatic juice from the pancreas and bile from the liver, via the common bile duct.

The small intestine also produces digestive juices from cells in the intestinal mucosa (lining). These digestive juices are full of enzymes and are also alkaline to neutralise the strong stomach acid. It is the intestines' digestive secretions pancreatic juice and bile which finalise the chemical digestion of our food, and it is here that most of the absorption of nutrients and water takes place.

The surface area of this organ is enormous, due to the folds of its lining, and to the villi and microvilli. These are the tiny projections which cover its lining and create a much larger suface area for absorption. The small intestine is well serviced by blood and lymph vessels and nerves. You will remember that it is the lymph system that transports the digested fats from the digestive system and the circulatory system picks up all the other nutrients. Segmented peristalsis provides motility.

The Liver is the most important organ in the body. It performs thousands of different functions and can be described as a major factory and storehouse. All nutrients absorbed into the blood stream are carried to the liver, first, and then distributed to other parts of the body. The liver's role in the digestive process is the production of bile. Bile salts in the bile emulsify fats, breaking them down into tiny micelles ready to be further digested by the pancreatic enzymes.

The Gall Bladder is located just below the liver. This organ concentrates and stores bile. When required for digestion, bile passes from the gall bladder along the common bile duct and into the small intestine at the duodenum.

Gall Stones. Bile is made up primarily of Bile Salts, Cholesterol, Lecithin and Water. The gall bladder removes some of the water to concentrate the bile. Lecithin is an emulsifier of fats. Gall stones can form if there is insufficient bile salts or lecithin, or if there is excessive cholesterol. The cholesterol crystallises to form gall stones (biliary calculi). Bile also contains a waste product fromthe destruction of old red blood cells. This 'bile pigment' is called bilirubin and passes out through the intestines with the bile and is excreted. Bilirubin is responsible for part of the colouring of the faeces. If a gall stone passes out of the gall bladder and lodges in the common bile duct, it will obstruct the flow of bile to the intestines. This can have serious consequences as it means that fats in the diet will no longer be properly digested, and we know that fats are a vital fuel for the metabolic processes. It also means that the liver will be unable to remove bilirubin and it will remain in the circulation and collect in other tissues, giving the skin and eyes a yellow colour. This condition is know as jaundice and is the most common cause of this complaint.

The Pancreas, is a small elongated organ which contains two principal types of glands. The endocrine glands of the pancreas secrete the hormones insulin and glucagon for sugar regulation. The exocrine glands are those which participate in the digestive processes and secrete a mixture of the vitally important digestive enzymes and bi‑carb soda. This mixture is collectively known as pancreatic juice, and is responsible for the final stage of chemical digestion of all foods. The bi‑carb soda helps to neutralise stomach acid in the intestines.

The importance of the pancreas is grossly underrated. The pancreas comes under the control of the liver and both of these organs need the greatest of care if you are to have good health.

Both bile and pancreatic juices share the Common Bile Duct for the passage to the duodenum. You can appreciate that a blockage low in this duct, where it has joined and is serving both of these organs, will have serious consequences.

The Colon is the site for the final stages of digestion and absorption of nutrients. Most nutrients and water have already been absorbed (about 90% in the small intestine). The colon is also responsible for the manufacturing of certain vitamins and for the formation and expulsion of faeces.

The colon is an elastic pocketed tube of about 1.5m (5 ft) in length. The pockets are known as Haustras, and the food is further mixed in the colon by haustral churning and moved along by mass peristalsis. A large colony of bacteria live in the colon. They comprise some 80% friendly bacteria such as Lactobacillus Acidophillus and Lactobacillus Bifidus, and about 20% Yeast (fungi). They can survive in the haustras, because of the relatively slow motility of this organ. It is estimated that an adult carries some 4kg of this intestinal flora inthe gut. These bacteria digest what is left of the chyme and in return they produce some of the vitamins that we need. Specically some of the B Group vitamins like B12 and Vitamin K. The last of the water is absorbed from the chyme in the colon and this leaves the harder residue knows as faeces.

Bowel Impaction is the result of faecal wastes which collect and harden in the haustras. This rotting material remains in the bowel and favours the proliferation of anaerobic (without oxygen) bacteria. These bacteria give off toxic wastes and these wastes, combined with the old and rotting debris, are abosrbed across the wall of the colon and into our blood stream. This impacted condition results in Auto Toxemia. It causes inflammation of the bowel and bowel pocketing.

Bowel pocketing is known as Diverticulitis and is a serious and uncomfortable condition. Good quality food with plenty of roughage is the first step in correcting these conditions. Plenty of water is also important and garlic in large doses, for its antiseptic properties is very helpful. Yoghurt will help reconstitute the friendly bacteria in the bowel. Bowel cancer is a major cause of death in our society. The need of regular bowel movements, at a rate of at least 1‑2 per day is an absolute priority in restoring health.

Diarrhoea results from an inflamed bowel and causes the chyme to pass through too rapidly. This does not allow enough time for the absorption of nutrients, particularly minerals. Any inflammatory condition of the bowel, which results in chronic diarrhoea, will mean a lack in most minerals, particularly potassium. Dehydration also becomes a problem, and so plenty of water must be supplied. Diarrhoea can result from intestinal putrification, allergy, infection or stress. In any of these conditions, good quality, high fibre food is always indicated.

Broad Spectrum Antibiotics are very efficient at killing bacteria, including all of the necessary intestinal flora in our colons. The indiscriminate use of these drugs upsets the balance of bacteria in the colon, and interferes with digestion and the manufacturing of vitamins. Reconstitution of the intestinal flora is always advisable during and following the use of these drugs. This can be done by using a B Vitamin Supplement, Yoghurt and possibly an Acidophillus Supplement and Garlic.

Digestion and Absorption are two processes which are essential for the survival and good health of the organism. Good liver function and bile production is essential, as is the healthy pancreatic function, providing sufficient pancreatic enzymes. Bowel health is vital. The colon must be working efficiently. It is the sewage system of your body and a blocked colon is no different to a blocked toilet in your house.

Water balance is also critical. We have seen that water is the most abundant substance in the body and we all need 1 litre (about 8 small glasses) of good clean water every day of our lives. This water should never be drunk with meals, as it will dilute the digestive juices and causes inefficient digestion. The GI uses some 8 litres of water per day. Most of this is reabsorbed in the intestines and the colon, and reused.

Digestive Problems

Faulty digestion is uncomfortable and will result in illness because many of the nutrients from the food that you eat will not reach your cells. The following dietary advice will assist in cases of improper digestion.

Burping, Belching and Indigestion

This is almost always mistaken as an 'over acid' stomach. As we have seen, most people are, in fact, likely to be Hypochlorhydric. Burping, belching and indigestion is more often a lack of stomach acid. Taking antacid preparations further reduces the little stomach acid that there is, with disastrous long term results.

Despite the 'low acid' condition of these stomachs, acidy tasting foods like oranges, grapefruits, tomatoes and capsicums will nearly always further aggravate the situation and should be avoided. Drinking fluids with meals further dilutes stomach acid and will impair digestion. Stress wil inhibit gastric secretions. Belching can occur from rushing meals, and gulping air. So:

1. Don't drink with meals. Drink half an hour before or after.

2. Improve the diet. Remove, or at least reduce Coffee, Tea, Sugary Foods, Processed Foods, Fried Foods, Salt and Alcohol. Also acid tasting foods like Tomatoes, Oranges, etc. Milk is better avoided.

3. Relax. Relax before eating. Take time with the meal and don't 'rush off' after it.

4. Supplement stomach acid. Sipping 2 tsps of Apple Cider Vinegar before or during the meal will help acidify the stomach. Severely Hypochlorhydric people will need HCI supplements. Use 2 before each meal (up to 6 can be taken in severe cases). These usually contain Betaine Hydrochloride, Pepsin and Glutamic Acid.

5. Use a good quality 'B' Complex, to provide nutrients for the production of gastric secretions and for energy and the nervous system (stress).

Bloating

This is usually abdominal and can occur premenstrually or could be caused by digestive inefficiency, food intolerance and more commonly, by yeast infection (candidiasis). Premenstrual bloating should be addressed using an improved diet plus a PMT supplement or Evening Primrose Oil.

The other three possible causes will all respond well to dietary improvement, and the use of digestive enzymes (containing ox bile and pancreatin).

Gastric and Duodinal Ulcers

These are nearly always stress related. This may be work stress, physical stress or emotional stress resulting from anger, fear, hopelessness and other causes. Ulcers can be 'brought on' by one day of stress. Ulcers are one of the few cases where the orthodox medical profession recognises the association between the emotions and illness. Duodenal ulcers are much more common than peptic ulcers. Treatment is the same for both. It appears that stress inhibit the secretions of mucous which would normally protect the stomach or duodenal wall from hydrochloric acid. The result is that the acid burns a hole in the wall and you have an ulcer. Similarly, stress can either inhibit HCI production or stimulate it. In the later case, this excess of acid can burn holes in the mucosa, resulting in an ulcer. It is the vegus nerve which carries the messages to stimulate HCI production, and it is not uncommon to find people who have suffered a vegotomy, which is a cutting of the vegus nerve in an attempt to inhibit excessive HCI production. This type of operation is almost unbelievable, and is attempting to treat the effect and not getting at the cause of the problem at all.

The treatment for ulcers is almost identical to that for burping, indigestion, etc. with one major exception. Never give stomach acid to someone who is suffering with an ulcer. The symptoms of ulcers are burning pains in the stomach. Gastric ulcers often cause pain after a meal. Duodenal ulcers cause pain before or between meals. The presence of ulcers can be confirmed by a doctor using a gastroscope. Please note, that emergency hospitalisation is necessary if an ulcer perforates or haemorrhages. So:

1. Same dietary restricitons as for burping etc. however these will need to be adhered to strictly and an actual 'low allergy diet' would be better. Milk is not suitable for ulcer sufferers.

2. Stress must be addressed and this may mean relaxation programmes, breathing, yoga and meditation.

3. Supplements. All nutrients will help, but the priorities could be Sodium Ascorbate, which is very soothing (10g/a day). 'B' Complex for Stress. Zinc for wound healing. Vitamins 'A' and 'E' for mucous membranes, circulation and scar tissue. Note that HCI must not be used. Digestive enzymes may be of assistance if there is flatulence.