The Starting Line (Mouth, Teeth, & Pharynx)
What is mastication?
Mastication increases the surface area of food particles, allowing digestive enzymes to work more efficiently.
What is peristalsis?
Peristalsis involves alternating waves of contraction and relaxation of longitudinal and circular muscles
What is the liver?
Hepatocytes (liver cells) continually manufacture bile, which is collected by bile canaliculi.
What is bicarbonate (or HCO3−)?
Bicarbonate raises chyme pH to roughly 7–8, creating the ideal pH environment for intestinal enzymes.
What is the mucosa?
The mucosa consists of an epithelial lining, lamina propria, and a thin muscularis mucosae layer.
What is salivary amylase?
Amylase breaks polysaccharides like starch down into shorter chains like maltose and dextrins.
What is the lower esophageal sphincter (or cardiac sphincter)?
Malfunction or weakness of this sphincter leads to Gastroesophageal Reflux Disease (GERD).
What is the gallbladder?
The gallbladder releases stored bile into the cystic duct upon hormonal stimulation by CCK.
What is pancreatic lipase?
Unlike salivary/gastric lipases, pancreatic lipase performs the vast majority of lipid breakdown.
What are villi?
Each villus contains a dense capillary network and a central lymphatic vessel called a lacteal.
What is a bolus?
Mucus secreted by the salivary glands helps bind food particles into a cohesive bolus.
What is chyme?
Chyme is created through mechanical churning mixed with gastric secretions.
What is emulsification?
Emulsification increases fat surface area so pancreatic lipase can digest lipids faster.
What are zymogens (or proenzymes)?
Trypsinogen is a primary example of a zymogen activated only once it reaches the intestinal lumen.
What are microvilli?
Microvilli increase the absorptive surface area of the small intestine to over 200 square meters!
What are the parotid, submandibular, and sublingual glands?
The parotid glands are the largest and sit anterior/inferior to the ear lobules.
What are rugae?
Rugae unfold as the stomach distends, allowing it to hold up to 1.5–2 liters of food/fluid.
What is bilirubin?
Accumulation of bilirubin in tissues leads to a yellowish discoloration known as jaundice.
What are pancreatic acini (or acinar cells)?
Acinar cells account for over 90% of pancreatic mass, reflecting its strong exocrine digestive role.
What are goblet cells?
Mucus produced by goblet cells protects tissues from enzymatic digestion and lubricates passage.
What is the epiglottis?
When swallowing, the larynx moves superiorly and the epiglottis folds downward to seal off the airway.
What is the pyloric sphincter?
The pyloric sphincter opens in small bursts, releasing only a few milliliters of chyme at a time.
What is the common bile duct?
The common bile duct joins with the pancreatic duct at the hepatopancreatic ampulla.
What is enteropeptidase (or enterokinase)?
Once activated, trypsin activates all other pancreatic zymogens in a cascading reaction.
What is the submucosal plexus (or Meissner's plexus)?
The submucosal plexus controls local secretions, while the myenteric plexus controls motility.