6-4. PHARYNX
The pharynx (pronounced "FAIR -inks") is a continuation of the rear of the mouth
region, just anterior to the vertebral column (spine). It is a common passageway for
both the respiratory and digestive systems.
6-5.
ESOPHAGUS
The esophagus is a muscular, tubular structure extending from the pharynx,
down through the neck and the thorax (chest), and to the stomach. During swallowing,
the esophagus serves as a passageway for the food from the pharynx to the stomach.
Section III. THE STOMACH
6-6. STORAGE FUNCTION
The stomach is a sac-like enlargement of the digestive tract specialized for the
storage of food. Since food is stored, a person does not have to eat continuously all
day. One is freed to do other things. The presence of valves at each end prevents the
stored food from leaving the stomach before it is ready. The pyloric valve prevents the
food from going further. The inner lining of the stomach is in folds to allow expansion.
6-7. DIGESTIVE FUNCTION
a. While the food is in the stomach, the digestive processes are initiated by
juices from the wall of the stomach. The musculature of the walls thoroughly mixes the
food and juices while the food is being held in the stomach. In fact, the stomach has an
extra layer of muscle fibers for this purpose.
b. When the pyloric valve of the stomach opens, a portion of the stomach
contents moves into the small intestine.
Section IV. THE SMALL INTESTINES AND ASSOCIATED GLANDS
6-8. GENERAL
a. Digestion is a chemical process. This process is facilitated by special
chemicals called digestive enzymes. The end products of digestion are absorbed
through the wall of the gut into the blood vessels. These end products are then
distributed to body parts that need them for growth, repair, or energy.
MD0006
6-6
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