Physiology: the swallowing process - Anatomy and physiology of the head, neck and chewing system
Physiology: the swallowing process
We do not only swallow to swallow the reduced and saliva-mixed food. Swallowing is also used to transport excess saliva, nasal and throat mucus to the esophagus. You take 800 to 1,000 times a day. This number of course varies per person: someone who chews gum all day produces more saliva and will therefore have to swallow more often than the average.
Three phases are distinguished in the swallowing process:
- Oral phase;
- Pharyngeal phase;
- Esophageal phase.
During the oral phase of the swallowing process, the reduced and saliva-mixed food is in the oral cavity. The tongue collects the food chunk on top of the tongue. The food is pressed against the palatum durum. The tongue moves the food piece backwards.
The moment the food chunk reaches the transition from the hard to the soft palate, the A-line, the pharyngeal phase begins. During the entire oral phase there is a random control over the swallowing process. We do not have to think when swallowing. However, the swallowing process can still be stopped at this stage under the influence of our will. This can happen if we suddenly feel a hair in the food chunk.
The pharyngeal phase of the swallowing process is completely reflex-based. Once the food has passed the A-line, the process can no longer be stopped. Because the airway and the foodway intersect in the pharynx, a number of safety mechanisms are "built in" there, for example the throat flap, the epiglottis. During the pharyngeal phase of the chewing process, the palatum molle and the uvula close the passage to the nose. Because the epiglottis tilts in front of the windpipe, no food can end up in the windpipe, the larynx, at the trachea / esophagus split.
After the food chunk has passed the pharynx, the safety devices of the nose and windpipe are set aside again. It is then possible to breathe again. In the pharyngeal phase of the swallowing process, breathing stops. Sometimes someone chokes. The epiglottis is then not properly tilted over the passage to the windpipe. This can happen when you suddenly have to laugh during the swallowing process. Through the air that comes out of the lungs, the voice valve rises. Food or drink then enters the windpipe. This immediately evokes a cough reflex. What ended up in the windpipe is blown out with great force. The closure to the nose sometimes leaves something to be desired, so that the food can literally come out of the nose.
The esophageal phase of the swallowing process is the phase in which the food is in the esophagus or esophagus. The food has passed the pharynx and is on its way to the stomach. This phase is very short (see image below).
The swallowing process.