NR228 Digestion
Let’s follow the path of a delicious ham and cheese sandwich with lettuce and pickles as it is eaten and digested! Start at the beginning and discuss the anatomical parts as well as the biochemical roles that contribute to this sandwich being turned into chemical energy. Be sure to include mechanical and chemical mechanisms, along with how they are metabolized in the body!
Digestion is the chemical breakdown of food molecules into smaller molecules that can be used by various cells within the body. The breakdown is initiated when food is ingested in the mouth and specific enzymes are exposed to components within the food molecules. Digestion begins in the mouth with mastication, or chewing, performed by the teeth. The purpose of chewing is to grant the food more exposure to enzymes, therefore allowing chemical digestion to occur faster. The presence of the food in the mouth stimulates exocrine glands. This causes the mouth to secrete digestive enzymes, namely salivary amylase. These secreted enzymes aid in the breakdown of foods, officially starting the digestion process. Carbohydrates in particular are mostly broken down by salivary amylase. Salivary amylase breaks starch, a popular carb, down to maltose. This means that the bread of the ham and cheese sandwich will notably be chemically altered at this point. It is because of this that bread begins to taste somewhat sweet if it is held in the mouth for some time. Muncins, or mucous, found within saliva help hold the food intact, creating a bolus. This allows the ingested material to be more easily managed as it passes through to the esophagus. Upon reaching the esophagus, the bolus is propelled by a movement called peristalsis. This wave-like contraction of smooth muscle moves the bolus to the cardiac sphincter, the door to which food enters the stomach. The stomach itself can store up to about two liters of food. Gastric juice produced by the gastric glands blends with the bolus. Found in gastric juice is
Digestion is the chemical breakdown of food molecules into smaller molecules that can be used by various cells within the body. The breakdown is initiated when food is ingested in the mouth and specific enzymes are exposed to components within the food molecules. Digestion begins in the mouth with mastication, or chewing, performed by the teeth. The purpose of chewing is to grant the food more exposure to enzymes, therefore allowing chemical digestion to occur faster. The presence of the food in the mouth stimulates exocrine glands. This causes the mouth to secrete digestive enzymes, namely salivary amylase. These secreted enzymes aid in the breakdown of foods, officially starting the digestion process. Carbohydrates in particular are mostly broken down by salivary amylase. Salivary amylase breaks starch, a popular carb, down to maltose. This means that the bread of the ham and cheese sandwich will notably be chemically altered at this point. It is because of this that bread begins to taste somewhat sweet if it is held in the mouth for some time. Muncins, or mucous, found within saliva help hold the food intact, creating a bolus. This allows the ingested material to be more easily managed as it passes through to the esophagus. Upon reaching the esophagus, the bolus is propelled by a movement called peristalsis. This wave-like contraction of smooth muscle moves the bolus to the cardiac sphincter, the door to which food enters the stomach. The stomach itself can store up to about two liters of food. Gastric juice produced by the gastric glands blends with the bolus. Found in gastric juice is