Swallowing reflex

SWALLOWING REFLEX

  • Swallowing centre is located in the brain stem (medulla oblongata).
  • Stimulation of the receptors in the soft palate, pharynx (posterior wall) and epiglottis (dorsal surface) by food material.
  • Sensory fibers emerge through vagus, glossopharyngeal and hypoglossal to mylohyoid and hypoglossal muscles.
  • Contraction of mylohyoid and hypoglossal muscles press the tongue against hard palate. Backward pulling of the tongue elevates soft palate.
  • The tongue forces the bolus in the opened oesophagus.
  • Pulling action of hyoid bone and larynx opens the oesophagus.
  • Larynx is closed by epiglottis.
  • This reflex involves internucial neurons from reticular formation.
  • Swallowing centre also activates the neighboring respiratory regulatory neurons.
  • This interrupts respiration during swallowing to avoid aspiration of food particles into respiratory passages.

Mechanism of regurgitation

  • Common in ruminants.
  • Initiated with closed glottis and raised palate.
  • Drop in intrathoracic and intraesophageal pressure due to inspiratory effort of the tongue.
  • Opening of cardia, clearing of cardia.
  • Extra reticular contraction (regurgitation contraction) pushed ruminoreticular cud to the mouth via esophagus.
Last modified: Thursday, 2 June 2011, 9:39 AM