You see the grilled cheese. Fresh out of the hot pan with cheddar cheese melting all down the sides. The nice wheat bread soaked with rich, creamy butter with some of it burnt on to form those perfect burnt edges. The wheat bread is mainly made up of carbohydrates and a little bit of protein. The cheddar cheese contains fat and protein. Lastly, the butter consists of almost all fat (so don’t put too much on there!). The first stop for this warm grilled cheese sandwich is in your mouth of course! Here, your tongue, which is a muscle, helps you initially break down your food with your teeth through a process called mastication or chewing; This is a process of mechanical digestion. The taste buds on your tongue will also send the signals it is receiving from the tasty grilled cheese to your brain. Saliva will help moisten the grilled cheese to make it easier to swallow. Saliva is produced by the parotid glands in your mouth. These salivary glands will expel the saliva on to the epithelial surface of your mouth. The enzyme amylase is also contained in your saliva to start processing the starches, like in your wheat bread, into dextrin and maltose. These enzymes in your saliva are an example of the chemical digestion the grilled cheese will go through. After you have chewed this food thoroughly, the next stop is the esophagus. No actual digestion occurs in this section, it is just a dynamic (muscular) way for food to get from the pharynx to the stomach. The esophagus uses a peristaltic movement to push the grilled cheese. This works as contraction similar to pulses that help push the grilled cheese into the stomach. As the grilled cheese enters the stomach it passes through the gastroesophageal or cardiac sphincter. After this it continues through the four sections of the stomach: the fundus, the body, the pylorus, and the duodenum. The grilled cheese will cause the stomach to expand, especially if you copious amounts of grilled cheese. Your meal will be temporarily stored here and be partially digested to then be released in increments to continue into the small intestine. The three layers of muscle on your stomach will churn the grilled cheese to break it up even more. Also in the stomach, to aid the digestion of the grilled cheese, is gastric juice and enzymes. This gastric juice will help decontaminate any toxins or bacteria that might have been on the grilled cheese. It will also absorb some nutrients from the grilled cheese. As there is protein found in the cheddar cheese and wheat bread, pepsin, found in gastric juice, helps partially digest them. Due to the fact that there is lactose in the cheddar cheese and a little bit in butter, the lactase enzyme will change this lactose to glucose. As there is maltose found in wheat bread and a little bit in cheddar cheese, the enzyme maltase will convert this to glucose. Also, the enzyme sucrase will convert the little bit of sucrose in the wheat bread to glucose. This enzyme will break the polysaccharides into disaccharides. Bile in your stomach will also help emulsify the fat found in the cheddar cheese and butter. Chyme is what eventually becomes of your grilled cheese which is a mixture of the partially digested food with other digestive secretions. The small intestine is the next stop for our already partially digested grilled cheese. Here, it will go on a 7 meter journey through the duodenum, jejunum, and Ileum of the small intestine. A peristaltic movement will move your food through the small intestine as well. Here more digestion of fats and carbohydrates will continue. An enzyme called pancreatic lipase will change this emulsified fat to glycerol and fatty acids in the small intestine from the butter and cheddar cheese. Another enzyme called pancreatic amylase will help you digest the carbohydrates from the wheat bread. Mainly in the jejunum is where the nutrients are absorbed after it has been broken down more in the duodenum. Following that, the ileum absorbs the bile acids from the chyme of the grilled cheese to be sent back to the liver and produce more bile. The last stop for your almost completely digested grilled cheese is the large intestine which is divided up into the cecum, the colon (ascending, transverse, descending, and sigmoid), and the rectum. The large intestine is what converts the liquid waste of the grilled cheese into a more solid form for easier bowel movements. It completes this by removing most of the water and some salt from the grilled cheese. This allows the body to stay balanced in its salt and water levels as it can choose how much to leave for disposal. The waste of the grilled cheese is most likely bacteria and food debris. After this it goes through the rectum to be disposed. That is the journey of grilled cheese in the digestive system!