Describe the physical (mechanical) and chemical digestion of the carbohydrate in an egg sandwich. The diagram should start with the nutrient (carbohydrate)and end with the products of digestion and mechanism of absorption.​

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This question indicates that the answer should focus on the digestion of carbohydrates found in an egg sandwich; therefore, I am going to ignore any proteins found in the sandwich.

Carbohydrates are an important part of a healthy diet. They are the sugars, starches, and fibers that are found in things like fruits and grains. Carbohydrates are also diverse in their complexity. They can be simple or complex—that depends on the number of sugars present. Simple carbohydrates contain one to two sugars per molecule and are referred to as monosaccharides and disaccharides. Complex carbohydrates, also called polysaccharides, are made of three or more sugars per molecule.

Carbohydrate digestion begins in the mouth. Technically speaking, all digestion begins in the mouth because the mouth mechanically breaks, tears, and grinds the food that is placed in the mouth. This happens to the carbohydrates from the sandwich that are chewed in the mouth; however, all that is happening is that the food is being physically broken down into smaller pieces. In addition to the teeth coming into contact with the food, saliva is also covering the food. That is super important for carbohydrate digestion because saliva contains amylase. Amylase is an enzyme specifically designed to chemically break down sugars/carbohydrates.

Once swallowed, the carbohydrate will move down the esophagus into the stomach. Here, the food will be mechanically churned and mixed with things like hydrochloric acid. The stomach acids actually stop the chemical digestion of the salivary amylase, so no further chemical digestion of carbohydrate happens in the stomach.

A few hours later, the stomach will empty its contents into the first section of the small intestine, which is called the duodenum. This is where a ton of chemical digestion now occurs, because the pancreas will secrete pancreatic amylase, lactase, sucrase, and maltase, and the carbohydrate sugars will be broken down into simpler and simpler sugars. The carbohydrate is then finally absorbed into the bloodstream through the villi that line the small intestine. The blood will then take that sugar to cells in the body, which use it to make ATP through the process of cellular respiration.

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