Wikijunior:Human Body/Digestive System
Our bodies need food to live and grow. Digestion is the process of taking the food and drink we eat and getting it ready for all the parts of the body to use. The digestive system breaks down food and carries it to all parts of the body.
What does the digestive system look like?
The digestive system looks like a long connected set of tubes and organs. It is about 10 meters long. It starts with the mouth. The esophagus is a long tube that connects the mouth to the stomach, which is within the ribcage. The stomach is a muscular bag-like structure and forms a J-shaped pouch and is located under the ribcage. The stomach connects to the small intestine. This is a long skinny tube that is about 7 meters long and winds forth and back within the abdominal cavity. This then connects to the large intestine which is larger in diameter and much shorter. The large intestine becomes the rectum and ends at the anus. The liver and the pancreas are glands that produce fluids that help with digestion - similar to the saliva produced in the mouth. This whole system includes tubes and all organs and glands form the alimentary canal where the digestion takes place.
What are the parts of the digestive system?
The digestive system starts with the mouth, where food and water enter our body. In our mouth, our teeth and tongue do part of the work of breaking food down into smaller pieces. Saliva contains the enzyme called salivary amylase or Ptyalin which converts the starch of food into maltose which is a complex sugar.
After we chew and swallow food, it goes down a tube called the esophagus. This tube goes from the mouth to the stomach by the movement of peristalsis, a rhythmic contraction and expansion. In the stomach, food is broken down more. The stomach has gastric juices containing hydrochloric acid, pepsin and mucus. Hydrochloric acid makes the food acidic, kills the germs and activates the pepsin. Pepsin digests the proteins. Mucus protects the inner lining of the stomach from the action of HCl and pepsin. After this happens, the food is passed on to the small intestine.
The small intestine is a very long twisting tube. This is where most digestion happens; here, food mixes with succus entericus (intestinal juice) secreted by the small intestine, trypsin (which digests protein), lipase (which digests lipids) secreted by pancreas, and bile juice secreted by the liver and stored in the gall bladder, which makes the food alkaline and emulsifies (breaks down) fats. These chemicals break the food down so it can be absorbed into the blood. The small intestine is lined with villi and blood vessels that absorb the nutrients from food.
Whatever is left over goes on to the large intestine where more villi absorb water. From there, the waste finally passes out of the body through the anus. The anal sphincter controls the process of defecation.
What is the function of the digestive system?
The job of the digestive system is to take the food we eat and make it usable for our bodies. The digestive system breaks down the food so our body can use it. It also separates out waste products that the body cannot use. The food ingested is broken down separately- proteins into amino acids, carbohydrates into glucose and lipids into fatty acids and glycerol.
How does the digestive system interact with other parts of the body?
The digestive system works with the circulatory system to get nutrients to all the parts of our body. After food is broken down and reaches the small intestine, blood vessels absorb the nutrients. The blood then carries the nutrients to cells all over the body.
How can you keep your digestive system healthy?
A big part of keeping your digestive system healthy is eating healthy food. Try not to eat too much or too little. Make sure to chew your food well. It is also good to include fiber in your diet. Fiber is found in fruits, vegetables, and whole grains. Eating yogurt can also add healthy bacteria to your body. Don't eat too much "junk food." This includes foods that are high in sugar or fat. If certain foods often make your stomach hurt or cause digestive problems, try cutting back or eliminating them from your diet.
Lastly, make sure to drink plenty of water. If you live somewhere where the water is not treated, make sure the water is boiled first this will kill any bacteria in the water and make it safe to drink.