A great many disorders of the body are directly connected with malfunctioning of the digestive system. In this way the digestive system has a direct influence on one’s daily life. You must have noticed for yourself that when you are experiencing digestive trouble you tend to be pessimistic and easily irritated. Conversely, a healthy digestive system allows one to be optimistic and cheerful. In short, the digestive system can help or prevent us enjoying life to the full. It is for this reason that yoga stresses the importance of maintaining the best possible health of this system. We do not intend this book to become a textbook on physiology, but we think that with a greater knowledge you will tend to treat the body with more respect. Moreover, a better understanding will help you to participate more actively and joyfully in your daily life, which of course is one of the main aims of yoga. For this reason we will briefly discuss the functions of the digestive system.
Digestive system – how it works
The food we eat cannot be absorbed directly into the body. It must first undergo a process of conversion into substances which can be directly conveyed into the bloodstream – the carrier and distributor of our foods throughout the body. This process is called digestion. (For a full understanding of the following text, refer to the diagram of the digestive system included overleaf.)
Digestion begins when food enters the mouth. The role the mouth plays in digestion is twofold: it physically breaks down the food into smaller fragments through the act of chewing while simultaneously secreting saliva through the salivary glands. The quantity of saliva secreted depends on the taste and look of the food, as well as on appetite. However, normally during the day one to two litres of saliva are secreted. Saliva contains the enzyme ptyalin, which starts to break down the starches present in the food into simpler forms of carbohydrates known as sugars. Saliva also contains bicarbonate, which neutralizes acids within the stomach. Many people take bicarbonate of soda to relieve hyperacidity, yet if enough time was given to allow a sufficient secretion of saliva there would be no need for such remedies. Therefore, for a good diges-tion, slow eating and adequate chewing are important to allow the saliva to complete its function properly as well as increasing one’s enjoyment of food.
After the food has been chewed sufficiently it passes through the throat (pharynx) to the food pipe (oesophagus). From there it is pushed down to the stomach by a series of rhythmic waves known as peristalsis. At the entrance to the stomach lies the cardiac sphincter, which allows the food to pass into the stomach.
Continue to: Digestive diet. How it works. Part II