Digestion in the Stomach

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  • Topic: Digestion, Gastric acid, Pepsin
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  • Published : October 2, 2012
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EXPERIMENT 12
DIGESTION IN THE STOMACH
ABSTRACT
Nutrients are absorbed in the body through the process of digestion, wherein foods are broken down into small particles suitable for further digestion. Digestive enzymes facilitate the digestion process and are restricted to specific segments of the digestive tract. In this experiment, three parts were done to analyze the chemical digestion in the stomach. Peptic digestion was found to occur only in the presence of acidic environment with the presence of the digestive enzyme, pepsin, which is activated by hydrochloric acid (HCl). Rennin, on the other hand, is also activated only in the presence of acidic environment. The milk subjected to specific temperature with the presence of an acid and an enzyme is found to have formed a curd. In gastric analysis, it is found out that the free and total acidity of gastric juice should be 1.82 and 1.92, respectively, in order for pepsin to work maximally. The presence of lactic acid was observed after the addition of gastric juice to FeCl3 solution which is indicated b the presence of canary-yellow colored solution.

DISCUSSION OF DATA AND RESULTSIn order for the nutrients in the food to be absorbed, they must first be broken down into particles that are small enough to be transported through carrier proteins into the epithelial cell that form the mucosal lining of the digestive tract. This process of breaking down food is called digestion, and occurs primarily within three particular segments of the digestive tract: the mouth, the stomach, and the small intestine.

Digestion occurs through two different processes: Physical digestion, where large chunks of food are ground into tiny particles; and chemical digestion whereby through the use of enzymes released into the digestive tract, large biomolecules are broken down into its individual monomers. Chemical digestion is essential for breaking food into particles that can be absorbed by the epithelium of the small and large intestine, and was the main focus of this experiment. The figure below shows the summary of the experiment.

Figure 1. Summary of the Steps Carried-Out in the Laboratory

There are many different substances that are secreted into the different segments of the digestive tract. Mucus, bile salts, bilirubin, hydrochloric acid (HCl), and sodium bicarbonate (NaHCO3) are just some of the substances mixed with the food as it passes through the digestive tract, and many of these substances facilitate the breakdown of food. However, the most important substances secreted for the purpose of digestion are the digestive enzymes. Digestive enzymes greatly enhance the rate at which the covalent bonds that link subunits together to form polymeric biomolecules are broken. Without the presence of these enzymes, chemical digestion would essentially not occur.

As observed from the previous experiments, the activity of enzymes is greatly influenced by different factors such as temperature, pH, and the action of inhibitor or activator. Temperature can have considerable influence on the rate at which enzyme-catalyzed reactions proceed wherein low temperatures result in slow reaction rates because overall kinetic energy is reduced. The same is true with very high temperatures. The rate of an enzyme-catalyzed reaction also slows down because high temperatures destabilize the noncovalent interactions that give enzymes the specific tertiary and quaternary structures that enable them to function as catalysts. Thus, it is important that the core body temperatures of humans be stable for the digestive process to persist. The relatively high temperature of the human body enables the digestive enzymes to break down food at near maximal rates. At the same time, enzyme activity is also influenced by the pH of the surrounding fluid. Enzymes have a particular pH where they proper conformation to function extensively. A significant deviation from the pH in which they function maximally will...
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