Anatomy and Physiology of the Gut

When food has been masticated in the mouth, it is swallowed and carried through a muscular tube called the oesophagus into the stomach.

The stomach produces gastric juices and together with gentle, rippling, ‘mixing waves’ produces chyme, a thin liquid. The stomach gradually moves its contents into the first part of the small intestine, the duodenum.

The intestines are made up of the small and large intestines or bowel. The small intestine is made up of a long tube and the major events of digestion occur, including 90% of all absorption of nutrients is within its bounds.

The small intestine is 3 metres in length and about 21⁄2 cm in diameter, making a very large surface area. Peristalsis, the gentle wave like action of the smooth muscles, propels chyme through the small intestine, and remains in the small intestine for 3-5 hours. Any undigested and unabsorbed matter then moves into the large intestine.

The large intestine, bowel or colon is about 1 1/2 metres long and 6 1/2 cm in diameter. The bowel excretes whatever food substances cannot be digested or absorbed as faeces. Faeces contain bile from the liver, which carries the waste products resulting from the breakdown of red blood cells, and large number of microbes.

The bowel also absorbs water, minerals and some ions. The flora or bacteria in the bowel are very important as they synthesise B vitamins and vitamin K and also protect against toxic bacteria.

The digestive ‘transit time’ is the time it takes for food to travel from the mouth to the anus. The transit time in humans should take approximately 12 – 24 hours. Sadly, however, it takes some people anything up to 72 hours or longer to complete this vital function. It is common, but not normal to find some people taking up to a week to have a bowel elimination.

Health Complaints

If you suffer from an auto-immune condition, allergies, fatigue, candida, mental-fogginess, weight gain, joint pain, or an arthritic type condition it is well worth healing your gut.  70% of your immune system lies in the intestinal walls. Your gut also makes the majority of the hormone Serotonin, the hormone responsible for a happy mood!


Serotonin is the key hormone that stabilizes our mood, feelings of well-being, and happiness. This hormone impacts your entire body. It enables brain cells and other nervous system cells to communicate with each other. Serotonin also helps with sleeping, eating, and digestion.

The gut produces 95% of serotonin.  There’s no doubt about it good health starts with efficient digestion.  If you are not absorbing your nutrients or eliminating your waste effectively, then you will never experience optimal health.

Common Digestive Complaints include

  • Diarrhoea, Constipation, Irritable Bowel Syndrome (IBS)
  • Diverticulosis or diverticulitis
  • Ingestion, Gas, Bloating
  • Intestinal Dysbiosis
  • Gluten-Intolerance, Celiac Disease
  • Leaking Gut, Food Allergies
  • Ulcers, Acid Reflux, Heart Burn, Burping
  • Pancreatic Enzyme Insufficiency

Miriam Young has specialised in gut issues for over 20 years and is dedicated in finding the cause of gut symptoms experienced by the individual.

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