Ch 16.3 -- GI System -- VTPP 435

Ch 16.3 -- GI System -- VTPP 435

Pharynx

-cavity at rear of throat
-passage for digestive and respiratory system

Tonsils

-on side walls of pharynx
-lymphoid tissues

Swallowing

entire process of food moving from mouth thru esophagus into stomach

Bolus

ball of chewed or liquid food

Swallowing Step

1) Swallowing when bolus pressed on palate

Oral Part of Oropharyngeal Stage

2) Tongue propels bolus to pharynx
3) swallowing center inhibits respiratory center in brain stem
4) elevation of uvula presents food from entering nasal passage ways

Pharyngeal Part of Oropharyngeal Stage

5) Position of tongue stops food from reentering mouth
6) alignment of vocal chords stop food from entering trachea
7) Epiglottis folds over closed glottis
8) Contraction of pharyngeal muscles pushes bolus thru opened pharyngoesophageal sphincter into esophagus

Beginning of Esophageal Stage of Swallowing

-Pharyngoesophageal sphincter closes
-oropharyngeal structures return to resting position and breathing resumes

Completion of Esophageal Stage

10) Peristalsis propels bolus down length of esophagus
11) Gastroesophageal sphincter relaxes as peristalsis pushes bolus into stomach

Larynx (voice box)

-first part of trachea
-where vocal folds are stretched
-contraction seals glottis entrance

Glottis

-Laryngeal opening
-sealed during swallowing

Epiglottis

-flap of cartilaginous tissue in front of glottis
-folds over closed glottis to prevent food from entering airway

Esophagus

-straight muscular tube
-extends between pharynx and stomach
-has 2 sphincters

Sphincter

-ring like muscular structure
-when closed, prevents passage thru tube it guards

Pharyngoesophageal Sphincter

-upper sphincter
-remains closed when not swallowing
-contracted to prevent air from going thru esophagus to stomach when breathing

Primary Peristaltic Wave

-triggered by swallowing center
-sweeps from start to end of esophagus
-forces bolus toward stomach

Peristalsis

-ring like contractions of smooth muscle that move bolus forward

Gastroesophageal Sphincter

-lower esophageal sphincter
-increases contraction during inspiration to prevent reflux of acid gastric contents into esophagus