Chapter 35, Problem 9A

Summary Introduction

To write:

The digestive processes that occur in the mouth, large intestine, stomach, small intestine, and esophagus.

Introduction:

The digestive system breaks down the food so that nutrients can be absorbed by the body. There are three primary functions of the digestive system. The digestive system absorbs food, breaks it down so that nutrients can be absorbed and removes that cannot be digested.

Explanation of Solution

The food reaches the mouth and the mechanical digestion of the food continues with the operation of mastication and the wetting touch of the saliva. Saliva produces salivary amylase, an enzyme that activates the absorption of starch in food; saliva also includes mucus, which lubricates hydrogen carbonate and food that provides the optimal pH for amylase to function. After chewing and digestion of starch, the food would be in the form of thin, circular slurry mass named a bolus. It would then pass down the esophagus and by the operation of the peristalsis into the stomach. Gastric juice in the stomach continues the absorption of proteins. Gastric juice contains primarily hydrochloric acid and pepsin. Since these two chemicals will destroy the wall of the stomach, the mucus is secreted from the stomach, creating a thin coating that serves as a barrier against the harmful effects of the chemicals. Around the same time as protein digestion happens, there is a mechanical mixture of peristalsis, which is a movement of muscle contractions that travels down the surface of the stomach. This allows the food mass to be more combined with the digestive enzymes. When the pyloric sphincter valve opens, the chyme goes into the duodenum where it is mixed with digestive enzymes from the pancreas and bile juice from the liver and ultimately passes to the small intestine where digestion starts. When the chyme is completely digested; it is processed into the blood of the large intestine. The indigestible substance then becomes more solid and it is called poop. The feces were expelled from the body by the anus.

Conclusion

Thus, the digestion process is done by the digestive system. The small intestine absorbed more nutrients during digestion.