How does the digestive system break down food?

Answer 1

Even before you take your first bite of food, your stomach is getting ready to digest your food, and will be digesting it for the next couple of hours or days, depending on what you ate.

When you first smell a food, or maybe even think about it, your mouth produces saliva, which helps to break down chemicals in the food. When you are done chewing, your tongue pushes the food down into the opening of your esophagus, which is the second part of the digestive system process.

The epiglottis is the small piece of tissue that helps the food go into your esophagus instead of somewhere else.

The esophagus is about ten inches long, and moves your food from the back of the throat to your stomach. Once the food has entered your esophagus, the muscles in the walls of the esophagus move in wavelike contractions - called peristalsis - to move the food through the esophagus, and into the stomach. All of this takes less than three seconds.

Your stomach is attached to the end of the esophagus, and has three jobs: store the food that has been eaten, break down the food into a liquid, and slowly empty the liquid into the small intestine. The muscles of the stomach mix all the food together with gastric juices, which help to kill any bacteria that might have been in the food. This thick liquid/paste is called chyme.

The small intestine, which is actually the most important step of digestion, is about one to two inches around, and is right below the stomach. If you stretched out an adult's intestine, it would be over twenty-two feet long. The small intestine serves to break down food even further, so that your body can absorb all the proteins, carbs, fats, etc. that it needs. The pancreas, gallbladder, and liver also help in this. The pancreas produces juices that help to digest fats and proteins. Bile from the liver absorbs fats into the bloodstream, and the gallbladder stores the bile, until it is needed by the liver.

All the nutrients then travel to the liver, while everything else that has not been digested goes to the large intestine.

Next is the large intestine (also known as the large bowel), which is made up of three parts (colon, rectum, cecus). It is about three to four inches around, and five feet long (if it was stretched out). This is where all the food that cannot be digested goes. Since it cannot be digested, it must leave the body; but before it goes, it passes through a part of the large intestine called the colon, which is where the body gets its last chance to absorb some of the nutrients from it that are left. Once it is done, it becomes a solid, and exits the body. In total, it takes about thirty-six to forty-eight hours or even longer for all the waste material to pass through the large intestine, and the wastes in the large intestine are also pushed through by the wavelike motion of peristalsis, as well as in the small intestine and esophagus.

The large intestine pushes the feces into the rectum, which is the last step in the digestive system process. This stays here until you are ready to use the bathroom. When your use the bathroom, the feces exit your body through the anus.

Answer 2

The mouth is the entrance to the human digestive system. Teeth gnash the food, breaking it down mechanically, while the three salivary glands release saliva containing the enzyme amylase, which breaks down starch and fat chemically. Saliva makes food easier to swallow by moistening it, as well as preventing the erosion of tooth enamel by modulating pH. After entering the body at the back of the throat, food travels down the esophagus, being transported not by gravity but by muscular contractions. This is why it is possible to eat while hanging upside down. The interior of the esophagus is very moist, which helps to further break down food and prevent damage to the rest of the digestive system. After moving through the esophagus portion of the digestive system, food and drink reaches the stomach, where it is further broken down into manageable pieces. Because the nutrients in food are ultimately meant to be consumed by cells, they must be broken into very small parcels for delivery. The primary agent of digestion in the stomach is gastric juices, which are produced in large amounts and can be very acidic. A secondary agent is muscular contractions within the stomach. After the stomach, the broken down food moves into the small intestine, the portion of the digestive system where most of the nutrient extraction takes place. As the food moves through the small intestine, it is mixed with bile, which is produced by the liver, as well as pancreatic juices, which perhaps unsurprisingly come from the pancreas. These two liquids help further the digestive process, breaking down the nutrients in food to the point where it can be absorbed by the blood. The inner intestine is home to the famous villi, tiny living extrusions which gather nutrients on a fine scale. The final components of the digestive system are the large intestine or colon, the anus, and the urinary tract, which separate the liquid matter from the solid matter and send them to their respective exit ports. Of course, the human digestive system is not 100% efficient, and there are many nutrients left over in this “waste”, which will be consumed happily by bacteria or sent through a waste processing plant.