GI Vocabulary & Terminology
What is deglutition?
(final part for digestion)
Deglutition involves voluntary (buccal) and involuntary (pharyngoesophageal) phases
What is the duodenum?
The duodenum is primarily dedicated to chemical digestion and neutralizing acidic chyme entering from the stomach.
What is water absorption (or reabsorption)?
The large intestine absorbs roughly 90% of the remaining water, along with key electrolytes like sodium and chloride.
What is pepsin?
Chief cells secrete inactive pepsinogen, which converts to active pepsin in the presence of acidic gastric juice (pH 1.5–2.0).
What is gastrin?
Gastrin secretion is stimulated by stomach distension and the presence of partially digested proteins.
What is segmentation?
Unlike peristalsis, segmentation functions primarily to mix contents with enzymes and mucosa.
What is the jejunum?
The jejunum features prominent plicae circulares (circular folds) and dense villi to maximize nutrient absorption into the blood.
What is the cecum?
Attached to the inferior tip of the cecum is the vermiform appendix, a vestigial organ with immune functions.
What are amino acids?
Amino acids are absorbed into enterocytes via active transport and enter the capillary blood network.
What is secretin?
Secretin acts as a chemical "fire extinguisher," neutralizing stomach acid entering the duodenum.
What is a lacteal?
Absorbed fats enter lacteals as chylomicrons because they are too large to enter blood capillaries directly.
What is the ileum?
The ileum ends at the ileocecal valve, which regulates the passage of remaining indigestible materials into the cecum.
What are teniae coli?
Tonic contractions of the teniae coli draw the colon wall together, creating small pouches called haustra.
What are disaccharidases (e.g., sucrase, lactase, maltase)?
A deficiency in the brush border enzyme lactase leads to lactose intolerance.
What is cholecystokinin (or CCK)?
CCK also acts on the brain to promote satiety, signaling that you are full.
What is the mesentery?
The mesentery prevents intestinal tangling and carries nerves, blood, and lymph vessels.
What are Peyer's patches?
Peyer's patches are key components of Gut-Associated Lymphoid Tissue (GALT) and monitor intestinal bacterial populations.
What is the gut microbiota (or microbiome / gut flora)?
Gut bacteria digest complex carbohydrates through fermentation, producing short-chain fatty acids as energy sources.
What are micelles?
Micelles allow nonpolar lipid breakdown products to diffuse passively across the apical membrane of enterocytes.
What is ghrelin?
Ghrelin levels rise significantly before meals and drop after food ingestion.
What are parietal cells?
Proton pumps (H+/K+ ATPase) on parietal cells actively transport hydrogen ions into the gastric lumen.
What are plicae circulares (or circular folds)?
Unlike gastric rugae, plicae circulares do not stretch or flatten out when the intestine is full.
What are mass movements?
Mass movements are frequently triggered by eating, known as the gastrocolic reflex.
What are chylomicrons?
Chylomicrons exit enterocytes via exocytosis and enter lacteals because they are too large to pass into capillaries.
What is the vagus nerve (or Cranial Nerve X)?
Parasympathetic stimulation via the vagus nerve enhances motility and enzyme secretion ("rest and digest").