It’s a typical day. After school you get home and you are starving, but you just want a snack. “What should I eat?,” you ask yourself. Then, after looking through the cabinets for a few minutes, you find Cheetos and decide to eat a few. With just the presence of those Cheetos in your sight, the digestion process begins in your 9 meter long digestive tract.
Crunch, Crunch, Crunch. As you munch on those first few Cheetos the digestion process begins in your mouth. Here, mechanical digestion begins to reduce the size of the Cheeto and mixes the food particles with saliva. The tongue helps mix and move the pieces of Cheeto throughout the mouth. The salivary glands in the mouth also contribute to the breakdown of the Cheetos in the mouth. They secrete amylase and mucus. The parotid glands begin chemical digestion on the Cheetos. It secretes a clear, watery fluid that is high in amylase. The enzyme, amylase, begins to breakdown carbohydrates into disaccharides. The other two salivary glands, the submandibular and the sublingual, secrete saliva containing mucus, which binds and lubricates the Cheeto particles for easy swallowing. Now the food has been formed into a bolus with the help of saliva, the tongue, and teeth. Next the bolus travels into the pharynx, where the epiglottis closes off the top of the trachea so no food can enter. Then it moves on to the esophagus, where peristaltic waves push the food toward the stomach. The food enters the stomach through the cardiac sphincter at the end of the esophagus.
Now the Cheetos have entered the stomach. The process of breaking down carbohydrates has already begun in the mouth and now more chemical
and mechanical digestion will take place in the stomach. Once the bolus has entered the stomach, it mixes with gastric juice, starts protein digestion, and absorbs a limited amount. Here the chief cells secrete the inactive enzyme pepsinogen and the parietal calls secrete hydrochloric acid. When mixed together, they create pepsin. The pepsin works to breakdown the two grams of protein present in the Cheetos. Hormones are also present in the stomach and aid in the digestion process. The hormone, gastrin, increases the secretory activity of gastric glands. In the stomach, some salt from the Cheetos is absorbed through the wall. The Cheetos that entered the stomach has now been transformed into a semifluid paste called chyme. Peristaltic waves push the chyme out of the stomach through the pyloric sphincter into the duodenum of the small intestine.
Now in the duodenum, accessory organs add their secretions to the chyme. First is the pancreas. It adds pancreatic juice to the chyme, which contains many enzymes that digest carbohydrates, fats, nucleic acids, and proteins. Pancreatic amylase begins to split the last of the fifteen grams of carbohydrates into double sugars. The pancreatic lipase breaks down the ten grams of fat into fatty acids and glycerol. There are three other protein-splitting enzymes called trypsin, chymotrypsin, and carboxypeptidase. These break the bonds between particular combinations of amino acids in proteins. The hormone, secretin, controls the secretion of pancreatic juices. When CCK and secretin join together, they slow down the activity of the stomach. The liver is another important accessory organ. It stores many substances, glycogen, iron, and vitamins A, D, and B12. It also helps maintain the normal concentration of blood glucose. The liver produces bile, which is important to digestion. The gall bladder stores, strengthens, and secretes the bile. CCK stimulates the gall bladder to secrete bile. Bile salts aid digestive enzymes. They break down fat globules into smaller droplets and enhance absorption. The Cheetos, in the form of chyme, are now traveling through the small intestine. In the small intestine, sucrase, maltase, and lactase split the double sugars into simple sugars, and intestinal lipase splits fats into fatty acids and glycerol. The villi, lining the small intestine, absorb monosaccharides, fatty acids, glycerol, electrolytes, and water along with the products of carbohydrate, protein, and fat digestion. Digestion of the Cheetos is completed in the small intestine by the accessory organs and the intestinal mucosa. After traveling through the duodenum, jejunum, and ileum of the small intestine, the remaining bits of the Cheetos exit through the ileocecal valve into the large intestine’s cecum.
Once in the cecum, the Cheetos continue on its path throughout the large intestine. In the first half of the large intestine, water and electrolytes are absorbed from what was left. The Cheetos travel through the ascending colon, transverse colon, descending colon, and the sigmoid colon. After this, it’s then stored as feces in the rectum.
Throughout the entire digestive process all sorts of materials were absorbed in all areas of the alimentary canal. The calories from the Cheetos are used as energy along with the carbohydrates that were broken down in the mouth and small intestine. The calcium from the Cheetos helps make bones and teeth healthy and strong, and iron is used in the blood. The two grams of protein were broken down in the stomach and small intestine by different enzymes. Fats were also broken down in the small intestine and used as energy or stored for later use. The pancreas and the small intestine played large roles in the breakdown of the Cheetos.
About five hours later, you feel the need to relieve yourself. You excuse yourself from the table and go to the bathroom. The waste left over from the Cheetos is mainly made of the little fiber the Cheetos contained, water, mucus, and bacteria. The feces are released from your body through the anal canal and out the anus. After several hours of traveling through your body, the waste products of the Cheetos finally exit the digestive track. Those fifteen Cheetos, you ate at three o’clock, went through a long journey through your body and later that night, at eight o’clock, were released from your body in a completely new form lacking much of the components they had before.
Anatomy and Physiology