9. The intestinal juice digests nearly all the different elements of the food, so that it is well fitted to complete the wonderful process by which the food is made ready to enter the blood and to nourish the body.
10. While the food is being acted upon by the bile, the pancreatic juice, and intestinal juice, it is gradually moved along the intestines. After all those portions of food which can be digested have been softened and dissolved, they are ready to be taken into the blood and distributed through the body.
11. Absorption.—If you put a dry sponge into water, it very soon becomes wet by soaking up the water. Indeed, if you only touch a corner of the sponge to the water, the whole sponge will soon become wet. We say that the sponge absorbs the water. It is in a somewhat similar way that the food is taken up or absorbed by the walls of the stomach and intestines. When the food is absorbed, the greater part of it is taken into the blood-vessels, of which we shall learn in a future lesson.
12. Liver Digestion.—After the food has been absorbed, the most of it is carried to the liver, where the process of digestion is completed. The liver also acts like an inspector to examine the digested food and remove hurtful substances which may be taken with it, such as alcohol, mustard, pepper, and other irritating things.
13. The Thoracic Duct.—A portion of the food, especially the digested fats, is absorbed by a portion of the lymphatic vessels called lacteals, which empty into a small vessel called the thoracic duct. This duct passes upward in front of the spine and empties into a vein near the heart.
How a mouthful of food is digested:
1. It is first masticated—that is, it is chewed and moistened with saliva.
2. Then it is swallowed, passing through the oesophagus to the stomach.
3. There it is acted upon, and a part of it digested by the gastric juice.
4. It is then passed into the small intestine, where it is acted upon by the bile, the pancreatic fluid, and the intestinal juice.
5. The digested food is then absorbed by the walls of the stomach and intestines.
6. The greater portion of the food is next passed through the liver, where hurtful substances are removed.
7. A smaller portion is carried through the thoracic duct and emptied into a vein near the heart.
BAD HABITS IN EATING.
1. Eating too Fast.—A most common fault is eating too fast. When the food is chewed too rapidly, and swallowed too quickly, it is not properly divided and softened. Such food cannot be easily acted upon by the various digestive juices.
2. Eating too Much.—A person who eats food too rapidly is also very likely to injure himself by eating too much. The digestive organs are able to do well only a certain amount of work. When too much food is eaten, none of it is digested as well as it should be. Food which is not well digested will not nourish the body.