Physiology of deglutition

1. PHYSIOLOGY OF
DEGLUTITION
----SAYAN BANERJEE

2. • DEFINITION:
– Deglutition or swallowing is the process by which food moves from
mouth into stomach.
• STAGES OF DEGLUTITION:
I. ORAL STAGE, when food moves from mouth to pharynx.
II. PHARYNGEAL STAGE, when food moves from pharynx to esophagus.
III. ESOPHAGEAL STAGE, when food moves from esophagus to stomach.

5. II. PHARYNGEAL STAGE
• It is a involuntary stage.
• Pharynx is a common passage for food and air-----
 Larynx lies anteriorly and continues as respiratory passage.
 Esophagus lies behind the larynx and continues as GI tract.

6. II. PHARYNGEAL STAGE (contd…)
All these movements arrest
respiration transiently for a
few seconds during
pharyngeal stage of
deglutition. It is called
DEGLUTITION APNEA.

7. II. PHARYNGEAL STAGE (contd…)

8. • It is also an involuntary stage.
• Esophagus forms the passage for movement of bolus from pharynx to the stomach.
• Movements of esophagus are specifically organized for this function and the
movements are called PERISTALTIC WAVES.
• PERISTALSIS means a wave of contraction, followed by the wave of relaxation of
muscle fibers of GI tract, which travel in aboral direction (away from mouth). By this
type of movement, the contents are propelled down along the GI tract.
• When bolus reaches the esophagus, the peristaltic waves are initiated. Usually, two
types of peristaltic contractions are produced in esophagus -----
– PRIMARY PERISTALTIC CONTRACTIONS
– SECONDARY PERISTALTIC CONTRACTIONS
II. ESOPHAGEAL STAGE

9. 1. Primary Peristaltic
Contractions
II. ESOPHAGEAL STAGE (contd….)

10. 2. Secondary Peristaltic
Contractions
II. ESOPHAGEAL STAGE (contd….)

11. ROLE OF LOWER
ESOPHAGEAL SPHINCTERII. ESOPHAGEAL STAGE (contd….)
Rarely, the
sphincter does
not relax
satisfactorily,
resulting in a
condition called
ACHALASIA.

13. • Auerbach’s plexus carrying sympathetic fibers lies between the
muscular layers. Recurrent laryngeal nerve supply the striated
muscles of upper third, while nonstriated fibers are supplied
through vagus nerve.
• An adult swallows 600 times/day with 50 swallows during sleep and
200 during eating. Swallowing depends on peripheral stimuli from
oropharynx, as well as messages from higher centers.

14. Gastroesophageal Reflux------
• Reflux of food (gastric content) into esophagus is prevented with
the following:
 Tone/Sphincteric action of gastroesophageal sphincter.
 Negative intra-thoracic pressure and slight positive intra-
abdominal pressure.
 PINCH-COCK EFFECT of the right crus of the diaphragm,
maintaining the forward bent of the GEJ.
 Rosette like MUCOSAL FOLDS of the gastric mucosa at the
cardia.
 Valve-like effect of the Esophago-gastric angle (ANGLE OF HIS).
• HEARTBURN (PYROSIS) refers to the feeling of substernal burning
and is highly specific of gastroesophageal reflux disease (GERD).