Digestive System Lecture: From Pharynx to Small Intestine

Vocabulary flashcards covering major anatomical structures, physiological processes, cell types, secretions, disorders, and pharmacology discussed in the lecture on the pharynx, esophagus, stomach, and small intestine.

Pharynx

A common passageway for both digestion and respiration located between the mouth and esophagus, lined with stratified squamous epithelium.

Stratified Squamous Epithelium

Multi-layered protective tissue that can be sloughed off and rapidly replaced; lines the pharynx and esophagus.

Peristalsis

Wavelike smooth-muscle contractions that propel a bolus of food through the esophagus and along the digestive tract.

Esophagus

Muscular tube posterior to the trachea that carries food from the pharynx to the stomach and passes through the diaphragm at the esophageal hiatus.

Esophageal Hiatus

Opening in the diaphragm through which the esophagus passes into the abdominal cavity.

Hiatal Hernia

Condition in which part of the stomach protrudes upward through the esophageal hiatus, often causing pain or reflux.

Esophageal Sphincter (Lower)

A weak, non-true sphincter at the junction of esophagus and stomach that limits but does not fully prevent reflux of gastric contents.

Dysphagia

Difficulty in swallowing due to obstruction or neuromuscular problems.

Gastroesophageal Reflux Disease (GERD)

Chronic backflow of acidic stomach contents into the esophagus; commonly called reflux.

Heartburn

Burning sensation in the chest caused by acidic gastric contents irritating the esophageal lining during reflux.

Stomach

Muscular organ that stores, churns, and chemically digests food while producing chyme and intrinsic factor.

Chyme

Semi-fluid, acidic slurry of partially digested food created in the stomach.

Intrinsic Factor

Glycoprotein secreted by the stomach that is essential for vitamin B₁₂ absorption in the small intestine.

Rugae

Large folds in the stomach lining that allow expansion as the organ fills.

Gastric Pits

Microscopic depressions in the stomach mucosa that open into gastric glands.

Parietal Cells

Stomach gland cells that secrete hydrogen and chloride ions, which combine in the lumen to form hydrochloric acid.

Chief Cells

Stomach cells that secrete the inactive enzyme precursor pepsinogen.

Pepsinogen

Inactive zymogen released by chief cells; converted to pepsin by stomach acid.

Pepsin

Active proteolytic enzyme in the stomach that breaks down proteins into peptides.

Gastric Juice

Mixture of hydrochloric acid, enzymes, and mucus produced by gastric glands to aid digestion.

Hydrochloric Acid

Strong acid formed in the stomach lumen; lowers pH, kills microbes, and activates pepsinogen.

Proton Pump Inhibitors (PPIs)

Medications (e.g., Prilosec, Prevacid) that block stomach H⁺/K⁺ ATPase pumps, reducing acid production.

Duodenum

First 8-inch segment of the small intestine where acidic chyme is neutralized and bile and pancreatic enzymes enter.

Jejunum

Middle, nutrient-absorbing portion of the small intestine characterized by abundant plicae and villi.

Ileum

Final segment of the small intestine; contains Peyer’s patches (MALT) and ends at the ileocecal sphincter.

Ileocecal Sphincter

Valve controlling passage of intestinal contents from the ileum into the large intestine (cecum).

Plicae Circulares

Permanent circular folds of the small-intestinal mucosa/submucosa that increase surface area for absorption.

Villi

Fingerlike projections on plicae that house blood capillaries and lacteals to absorb nutrients.

Lacteal

Lymphatic capillary inside each villus that absorbs dietary fats too large for blood capillaries.

Segmentation

Localized rhythmic contractions of the small intestine that mix chyme and enhance contact with mucosa.

Common Bile Duct

Duct through which bile from the liver and gallbladder enters the duodenum.

Bile

Emulsifying fluid produced by the liver (stored in gallbladder) that aids fat digestion.