Esophagus Flashcards
EMBRYOLOGY of ESOPHAGUS
The esophagus develops from the postpharyngeal foregut and can be
distinguished from the stomach in the 4 wk old embryo.
At the same time, the trachea begins to bud just anterior to the developing esophagus; the resulting laryngotracheal groove extends and becomes the lung.
Length of esophagus
The length of the esophagus is 8-10 cm at birth and doubles in the first 2-3 yr of life, reaching approximately 25 cm in the adult.
Factors for anti reflux
Intraabdominal location of both the distal esophagus and the lower esophageal sphincter (LES) is an important antireflux mechanism,
because an increase in intraabdominal pressure is also transmitted to the sphincter, augmenting its defense.
Swallowing can be seen at what weeks of intrauterine
16-20 wise of gestation
hallmark of lack of normal swallowing or of esophageal or upper gastrointestinal tract obstruction
Polyhydromnios
Epithelial layer of oesophagus and it’s importance
Non keratinised stratified squamous epithelium, which abruptly changes to simple columnar epithelium at the stomach’s upper margin at the gastroesophageal junction (GEJ)
Chronic irritation by gastric contents can result in
Morphometric changes (thickening of the basal cell layer and lengthening of papillary ingrowth into the epithelium) and subsequent metaplasia of the cells lining the lower esophagus from squamous to columnar.
Normal esophagus pressure (LES)
At rest, the tonic LES pressure is normally approximately 20 mm Hg; values <10 mm Hg are usually considered abnormal, although it seems that competence against retrograde flow of gastric material is maintained if the LES pressure is >5 mm Hg
Normal peristaltic movements of esophagus
The normal esophageal peristaltic speed is approximately 3 cm/sec; the wave takes 4 sec or longer to traverse the 12 cm esophagus of a young infant and considerably longer in a larger child.
Facial stimulation by a puff of air can induce swallowing and esophageal peristalsis in healthy young infants, a reflex termed the Santmyer swallow.
Transient LES relaxation
Transient LES relaxation, not associated with swallowing, is the major mechanism underlying pathologic reflux
Protective mechanisms to prevent aspiration
The protective functions include the
LES tone,
the bolstering of the LES by the surrounding diaphragmatic crura, and
the backup protection of the UES tone
Secondary peristalsis
Secondary peristalsis, akin to primary peristalsis but without an oral component, originates in the upper esophagus, triggered mainly by GER, and thereby also clears refluxed gastric contents from the esophagus.
protective reflexes against aspiration
esophago-UES contractile reflex, the pharyngo-UES contractile reflex, the esophagoglottal closure reflex, and 2 pharyngoglottal adduction reflexes. The last 2 reflexes have chemoreceptors on the laryngeal surface of the epiglottis
T he most common esophageal disorder in children is
GERD, which is from retrograde return of gastric contents into the esophagus.
Esophagitis etiology
GERD,
by eosinophilic disease,
by infection, or
by caustic substances
