QS Study

Deglutition or Swallowing is a complicated mechanism in which food passages from mouth to the stomach. It can be initiated voluntarily, but thereafter it is almost entirely under reflex control. The swallowing reflex is a rigidly ordered sequence that propels food from the mouth to the stomach. It is the process of passing food from the mouth into the esophagus where it is transported to the stomach so that the main processes of digestion and nutrient absorption can commence.

  • Swallowing center – An area in the medulla and lower pons. (N. tractus solitarius, N. ambiguous)
  • Nerves – Trigeminal, Glossopharyngeal, Vagus.

Fig: major events involved in the swallowing reflex

Stage of Deglutition

Voluntary stage – It initiates the swallowing process by movement of the tongue. Patients with impairment of the oral stage may experience difficulty creating a seal around a fork or spoon with their lips, chewing solid consistencies, forming chewed food into a bolus or moving the bolus to the back of the mouth.

Pharyngeal stage – It is involuntary and constitutes the passage of food through the pharynx to the esophagus. If the pharyngeal phase is impaired, food or liquid can move into the throat before the automatic swallow is triggered, resulting in food or liquid touching the vocal folds or penetrating the vocal folds and moving into the lungs.

When food bolus is on the pharynx, there starts a wave of involuntary contraction in pharyngeal muscles that push the material into the esophagus. Inhibition of respiration and glottic closure are part of the reflex response.

An esophageal stage – An involuntary stage which promotes passage of food from the pharynx to the stomach. When food reaches the lower end of the esophagus, the lower esophageal sphincter opens to allow the food to enter the stomach. A peristaltic ring contraction esophageal muscle forms behind the material, which a then swept down the esophagus at a speed of approximately 4 cm/s.

Related Information –

While eating and drinking – 200

While awake without food – 350

While sleeping -50

Total no of swallows per day = 600.