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Physiology

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GIT

Question
4 out of 19
 

Deglutition peristalsis of oesophagus: (AIPG 2009)



A Primary
B Secondary

C Tertiary
D Quaternary

Ans. A Primary

I. Esophageal peristalsis can be initiated by deglutition ("primary" peristalsis) or local distention ("secondary" peristalsis).

II. Deglutition is one of the most complex reflex neural activities.

III. The initial phase is voluntary when food is chewed, mixed with saliva and formed into a bolus before being pushed to the posterior pharynx by the tongue. Receptors in the posterior pharynx are then activated to initiate the involuntary phase of deglutition, which involves carefully sequenced contraction of numerous head and neck muscles.

  1. Secondary peristalsis refers to peristalsis activated by esophageal distention.
  2. This can occur physiologically by food left behind after the primary peristaltic wave has passed, or by refluxed contents from the stomach.
  3. Unlike primary peristalsis, secondary peristalsis is not accompanied by deglutition with associated pharyngeal and upper esophageal sphincter motor function.
  4. In the striated muscle esophagus, distention activates a peristaltic reflex that is mediated by central mechanisms; distention activates vagal afferents, which in turn leads to sequential vagal efferent discharge to the striated musculature of the proximal esophagus.

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