Gastrointestinal Anatomy: Esophagus and Stomach

Comprehensive vocabulary flashcards covering the anatomical structure, innervation, histology, motility, and clinical pathologies of the esophagus and stomach based on the lecture transcript.

Esophagus

A muscular tube measuring approximately $25\text{ to }30\,\text{cm}$ in length, located posterior to the trachea and anterior to the vertebral bodies, extending from the level of the $\text{C6}$ vertebra to approximately $\text{T10}\text{ to }\text{T12}$.

Lower Esophageal Sphincter (Cardiac Sphincter)

A physiological muscular valve located at the junction where the distal esophagus enters the cardia of the stomach.

Bolus

A lubricated, rounded mass of chewed food formed in the oral cavity through mastication and mixing with saliva before being swallowed.

Portacaval Anastomosis (Esophageal)

A vascular junction where venous drainage of the upper and middle esophagus flows into the caval system via the superior vena cava, while the lower esophagus drains into the portal vein.

Stratified Non-Keratinized Squamous Epithelium

A multi-layered protective epithelial lining adapted to withstand friction, found lining the oral cavity, esophagus, and lower anal canal.

Secretomotor Movement

A specialized tube movement controlled within the submucosa that stimulates the secretion of mucus to serve as a lubricant and solvent.

Peristalsis

Involuntary, coordinated wave-like contractions and relaxations of smooth muscle layers that propel luminal contents through a tubular organ.

Segmentation

A localized pattern of motility where adjacent segments of smooth muscle alternately constrict and relax to churn and mix contents.

Submucosal Plexus

An autonomic nerve network situated in the submucosal layer of the gut wall that regulates local glandular mucus secretion and blood flow.

Myenteric Plexus

An enteric nerve network located within the tunica muscularis between the circular and longitudinal muscle layers that regulates gastrointestinal motility.

Esophageal Atresia

A congenital malformation in which the distal esophagus ends blindly rather than continuing into the stomach as an open, continuous tube.

Tracheoesophageal Fistula

An abnormal epithelialized conduit or connection developing between the trachea and the esophagus.

Achalasia (Cardiospasm)

A motor disorder of the esophagus resulting from defective embryonic neural migration into the intramural plexuses (or from stroke/trauma), impairing peristalsis and the ability to swallow.

Barrett's Esophagus

A pathological adaptation caused by chronic gastroesophageal reflux disease ($\text{GERD}$) wherein the normal stratified squamous epithelium of the lower esophagus undergoes metaplasia into simple columnar epithelium.

Chyme

A semi-fluid, soupy slurry of partially digested food mixed with acidic gastric secretions produced by mechanical churning in the stomach.

Rugae

Prominent longitudinal mucosal folds in the internal lining of the stomach and urinary bladder that permit expansion and shrinkage.

Oblique Muscle Layer

An innermost muscular sublayer unique to the tunica muscularis of the stomach that facilitates mechanical churning.

Hypertrophic Pyloric Stenosis

A congenital hypertrophy of smooth muscle in the pyloric sphincter, characterized by projectile, nonbilious vomiting after feeding and an olive-sized mass palpable at the right costal margin.

Pyloromyotomy

A surgical incision and removal of only the hypertrophied longitudinal muscle of the pyloric sphincter, leaving the underlying circular muscle, submucosa, and mucosa intact.

Chief Cells

The most numerous secretory cells of the gastric glands, responsible for synthesizing and secreting the inactive zymogen pepsinogen.

Parietal Cells

Specialized gastric gland cells that secrete hydrochloric acid ($\text{HCl}$) and intrinsic factor.

G Cells

Enteroendocrine cells restricted to the pylorus and pyloric antrum that secrete the peptide hormone gastrin directly into the bloodstream.

Gastrin

A peptide hormone produced by G cells that targets parietal cells to increase their mitotic activity and stimulate the secretion of hydrochloric acid.

Intrinsic Factor

A glycoprotein chaperone secreted by parietal cells that binds to dietary vitamin $B_{12}$ to enable its subsequent absorption in the terminal ileum.

Pepsinogen

An inactive enzymatic precursor secreted by chief cells that is cleaved and activated by hydrochloric acid into pepsin to break peptide bonds in dietary proteins.

Sliding Hiatal Hernia

A herniation where the cardia of the stomach slides upward through the esophageal hiatus into the thoracic cavity, forcing open the lower esophageal sphincter and causing heartburn and regurgitation.

Paraesophageal Hiatal Hernia

A hernia in which the cardia remains in its anatomical position while the gastric fundus herniates alongside the esophagus through the esophageal hiatus into the thoracic cavity.

Fundoplication

A surgical procedure for hiatal hernia repair where the gastric fundus is wrapped around the lower esophagus and cardia to anchor the stomach below the diaphragm.

Gastritis

Inflammation or irritation of the gastric mucosa that may be classified as acute or chronic, erosive or non-erosive.

Hemigastrectomy (Antrectomy)

Surgical resection of the pylorus and pyloric antrum performed in refractory peptic ulcer disease to eradicate acid-stimulating G cells.