Digestive system and excretion – food is taken in through the mouth and oesophagus to the stomach. The liver, gall bladder, spleen and pancreas all play a part in digestion. The food passes through the long and small intestine, and is finally excreted through the rectum and anus. The appendix may be a vestigial organ no longer of much use, though it may play a part in the immune system. When you eat, food takes 6 – 8 hours to pass through the small intestine and then spends some time in the large intestine before it is excreted. The time is typically quoted as 40 – 50 hours from ingestion to excretion, but it depends a lot on what you eat (and women are slower than men). Meat takes longer; about 2 days to pass through would be quite normal. Vegetarians on a high fibre diet of nuts and fruits and vegetables can pass a meal through in as little as 12 hours. If food passes too quickly through the intestines the proper absorption of vitamins and minerals may not occur, but if the food remains in the bowels for a long period this can lead towards fermentation and disease.
It has been said that the origin of all disease in the body begins in the bowels – a healthy intestine leads to a healthy body. Refer also to discussion on the Enteric Nervous System.