Activities Occurring in the Mouth, Pharynx, and Esophagus Food Ingestion and Breakdown Flashcards
Once food has been placed in the mouth,what two breakdowns occur
both mechanical and digestive (chemical) processing begins. First the food is physically broken down into smaller particles as it is chewed. Then, as the food is mixed with saliva, salivary amylase begins the digestion of starch, chemically breaking it down into maltose (see Figure 14.13). The next time you eat a piece of bread, chew it for a few minutes before swallowing it. You will notice that it begins to taste sweet as the sugars are released.
Saliva is normally secreted continuously to keep the mouth moist, but
when food enters the mouth, much larger amounts of saliva pour out. However, the simple pressure of anything put in the mouth and chewed, such as rubber bands or sugarless gum, will also stimulate the release of saliva. Some emotional stimuli can also cause salivation. For example, the mere thought of a hot fudge sundae will make many a mouth water. All these reflexes, though initiated by different stimuli, are brought about by parasympathetic fibers in cranial nerves VII and IX.
sentially no food absorption occurs in the mouth. (However,
some drugs, such as nitroglycerine, are absorbed easily through the oral mucosa.) The pharynx and esophagus have no digestive function; they simply provide passageways to carry food to the next processing site, the stomach.
swallowing cordinayion and how it works togheter
For food to be sent on its way from the mouth, it must first be swallowed. Deglutition (de″gloo-tish′un), or swallowing, is a complex process that involves the coordinated activity of several structures (tongue, soft palate, pharynx, and esophagus). It has two major phases, the buccal and the pharyngeal-esophageal. The first phase, the voluntary buccal phase, occurs in the mouth. Once the food has been chewed and well mixed with saliva, the bolus (food mass) is forced into the pharynx by the tongue. As food enters the pharynx, it passes out of our control and into the realm of reflex activity.
The second phase, the involuntary pharyngeal-esophageal phase,
transports food through the pharynx and esophagus. The parasympathetic division of the autonomic nervous system (primarily the vagus nerve) controls this phase and promotes the mobility of the digestive organs from this point on.
the non food paths are blocked off.
All routes that the food might take, except the desired route further into the digestive tract, are blocked off. The tongue blocks off the mouth, and the soft palate closes off the nasal passages. The larynx rises so that its opening (into the respiratory passageways) is covered by the flaplike epiglottis. Food is moved through the pharynx and then into the esophagus inferiorly by wavelike peristaltic contractions of their muscular walls—first the longitudinal muscles contract, and then the circular muscles contract. (The events of the swallowing process are illustrated in
what happens if we laugh while eating
If we try to talk or laugh while swallowing, we confuse our bodies with mixed messages, and as a result food may enter the respiratory passages. This triggers still another protective reflex—coughing—during which air rushes upward from the lungs in an attempt to expel the food.
what does gravity play a role in this.
If we try to talk or laugh while swallowing, we confuse our bodies with mixed messages, and as a result food may enter the respiratory passages. This triggers still another protective reflex—coughing—during which air rushes upward from the lungs in an attempt to expel the food.
