Page 1 of8S3 Lec 2: Gastrointestinal Tract by Dr. Voltaire YabutDEFINITION OF TERMS Heartburn =Retrosternal burning pain yUsually due to regurgitation of gastric contents into lower esophagus Dysphagia = Difficulty in swallowing yCause: Esophageal muscle/ nerve dysfunction yResult: narrowing or obstruction of esophageal lumen with swallowing difficulty CONGENITAL ANOMALIES ECTOPIC TISSUE RESTS yCommon patches of ectopic gastric mucosa, sebaceous glands orpancreatic tissue yGastric or pancreatic secretion Inflammation and discomfort CONGENITAL CYSTS yPresent as mass lesions that need to be explained yDuplication of smooth muscle layers yBronchial (bronchogenic cyst) or lung tissue (pulmonary sequestration) ATRESIA AND FISTULAS yAgenesis (absence) = extremely rare yAtresia and fistula present early with immediate regurgitation upon feeding yTracheoesophafeal fistula can take one of the several forms oType A = blind upper and lower esophageal segments oType B = fistula between upper segment and trachea, no lowersegment oType C = blind upper segment with fistula between lower segment and trachea oType D = blind upper segment, no lower segment oType E = fistula between patent esophagus and trachea yMay be associated with congenital heart disease, neurologic problems, GU or other Gi malformations yClinical presentation: Aspiration, suffocation from food, pneumonia, fluid and electrolyte imbalance ESOPHAGUS NORMAL yOrigin: Cranial portion of foregut yDevelopment: Recognizable by the 3 rd week of gestation yAnatomy: hollow highly distensible muscular tube yLength oNewborn: 11 cm oAdult: 25 cm yPoints of luminal narrowing 1.At the cricoids cartilage 2.Alongside the aortic arch 3.At the anterior crossing of the left main bronchus and the left atrium 4.Where the esophagus pierces the diaphragm yHigh pressure areas oThose that remain contracted even in the resting phase 1.Upper esophageal sphincter (UES) 3 cm segment in the proximal esophagus At the level of the cricopharyngeus muscle 2.Lower esophageal sphincter (LES) 2 to 4 cm segment proximal to the gastroesophageal (GE) junction At the level of the diaphragm Function: prevent reflux of gastric contents Control of muscle tone: a.Decreased muscle tone ~(-) Tonix excitation by cholinergic neurons ~Inhibitory nonadrenergic/ noncholinergic neurons ~Nitric oxide (NO) ~Vasoactive intestinal peptide (VIP) b.Increased muscle tone ~Gastrin ~ PGF2~Serotonin ~ Substance P ~Acetylchol ine ~ Histamine ~Motili n ~ Pancreatic polypeptide yEsophageal Wall 1.Mucosa o(+) Smooth, glistening,pink-tan surface oComponents a.Epithelial (ep) layerNon keratinized, stratified squamous cells Underlying basal cells ~Comprise 10-15% of the mucosal thickness ~Reserve cells with high proliferating potential Specialized cells in the deeper layer~Melanocytes ~Endocrine cells ~Dendritic cells ~Lymphocytes b.Lamina propria Non epithelial portion of the mucosa Consists of areolar connective tissue ( CT), vascular structures and scattered leukocytes ³Papillae´ = Fingerlike extensions of the lamina propria into the epithelial layerc.Muscularis mucosae Longitudinally oriented smooth muscle bundles 2.Submucosa oLoose connective tissue containing: a.Blood vessels b.Lymphatics c.WBCs with occasional lymphoid follicles d.Nerve fibers (inc.Meissner¶s plexus) e.Submucosal glands Connected to the lumen by ducts lined by squamous ep. More concentrated in the upper and lower regions Secretion: Mucin- containing fluid for lubrication 3.Muscularispropria oComponents: a.Inner circular smooth muscle b.Intervening Auerbach plexus c.Outer longitudinal smooth muscle o Proximal 6-8 cm contain striated muscles of cricopharyngeus muscle 4.Adventitia/ Serosa oPresent only in a small segment of the intraabdominalesophagus Most are devoid of a serosal coat (in contrast to most of GIT) The rest (thoracic esophagus) is surrounded by fascia Vertebral level Anatomic part Distrance from incisor(For endoscopy) Start C6 Epiglottis 15 cm End T11 or T12 GE junction 40 cm B i e n A g N i n a I a n J o h n G R a c h e l M a r k J o c e l l e E d o G i e n a h J h o K a t h A y n z J e G l a d N i c k i e R i c o b e a r T e a c h e r D a d a n g N i a A r l e n e V i v s P a u l F . R i c o F . R e n M a i R e v s M a v i s J e p a y Y a n a M a y i S e r g e H u n g T o p e
