Nourah Al- Eyadhi - Spring 2008 (Directional Process Essay – 580 Words)
Food In, Then What?
Believe it or not, the digestive process starts even before you put food in your mouth. It begins when you smell something irresistible or when you see a favorite food you know will taste good. Just by smelling that homemade apple pie or thinking about how delicious that ice cream sundae is going to taste, you begin to salivate — and the digestive process kicks in, preparing for that first scrumptious bite. Groups of organs, such as the mouth, esophagus, stomach, and intestines, work together to perform this complex task. Digestion is the process of breaking down food from large molecules into small ones to make it easier for absorption. The three major steps involved in the digestive process are ingestion, digestion, and absorption.
Ingestion, which occurs in the mouth, is the first step of the digestive process. After food enters the mouth, the teeth chew it. Saliva, which is produced by the salivary glands, plays a major role in breaking down the food into smaller pieces. These small pieces travel to the stomach through the esophagus.
In the stomach, the second step of the digestive process begins. When the chewed food reaches the bottom of the esophagus, a valve lets the food enter the stomach. Contraction of the stomach wall mixes the food. Acidic gastric juices, which are secreted by the gastric glands in the stomach, help in mixing the food and in turning it intoa partial liquid so it will have the ability to move into the small intestine. In the small intestine, enzymes are secreted, and digestion is completed.
The last step in the digestive process is absorption. By the time food is ready to leave the stomach, it has been processed into a thick liquid called chyme (pronounced: kime), and this is when absorption takes place in the small intestine. The wall of the small intestine is lined with small, finger like projections called villi. Small molecules of food are absorbed by the huge number of villi. Some of these absorbed molecules enter the bloodstream to be distributed throughout the whole body.
If it's been a while since your last meal or if you even think about something tasty, you feel hungry. You eat until you're satisfied and then go about your business. But for the next 20 hours or so, your digestive system is doing its job as the food you ate travels through your body. The kinds and amounts of food a person eats and how the digestive system processes that food play key roles in maintaining good health.