BIOL 373 Unit 6b

Deglutition

The physiological name for the swallowing reflex

Cranial Nerve IX

The nerve containing sensory afferents for the swallowing reflex in the medulla

Lysozyme

Antimicrobial enzyme in saliva that attacks bacterial cell walls

Gastroesophageal Reflux Disease (GERD)

Heartburn caused by the failure of the Lower Esophageal Sphincter (LES) to close

Receptive Relaxation

The neurally mediated relaxation of the upper stomach to store food

Gastric Dumping Syndrome

The rapid entry of undigested chyme into the SI due to loss of stomach storage function

Chyme

The soupy mixture of food and gastric secretions produced in the stomach

Pepsin

The active endopeptidase that digests meat collagen; activated from pepsinogen by acid

Gastric Lipase

Enzyme co-secreted with pepsinogen by chief cells for minor fat digestion

Histamine

Substance from ECL cells that binds H2 receptors to promote acid secretion

Gastrin

Hormone from G-cells that stimulates acid secretion (direct and indirect)

Somatostatin

Negative regulator from D-cells that inhibits acid and pepsinogen secretion

Alkaline Tide

The rise in blood pH during gastric secretion due to bicarbonate absorption

H2 Receptor Antagonists

Drugs that block histamine action to treat peptic ulcers

Proton Pump Inhibitors (PPIs)

Drugs that block H+/K+-ATPase to stop acid production at the source

Peptic Ulcer

A hole in the gastric mucosa extending into the submucosa caused by acid damage

Enteropeptidase

The brush border enzyme that activates Trypsinogen into Trypsin

Trypsin

The master pancreatic enzyme that activates all other pancreatic zymogens

Enterohepatic Circulation

The recycling of bile salts from the terminal ileum back to the liver

Gastroileal Reflex

Reflex where food leaving the stomach triggers the relaxation of the ileocecal valve

Mass Movements

Wave-like contractions in the colon that occur 3-4 times per day to move feces

Osmotic Diarrhea

Diarrhea caused by unabsorbed solutes like lactose or sorbitol pulling water into the gut

Secretory Diarrhea

Diarrhea caused by bacterial toxins (like cholera) increasing Cl- secretion

Vibrio cholerae

The bacteria responsible for cholera, requiring a high dose unless gastric acidity is low

G-alpha Subunit

The part of the G-protein modified by cholera toxin so it cannot hydrolyze GTP

Adenylyl Cyclase

The enzyme persistently activated in cholera, leading to high intracellular cAMP

cAMP

The intracellular messenger that keeps the CFTR channel open during a cholera infection

CFTR Channel

The chloride channel that is persistently activated by cAMP in secretory diarrhea

Terminal Ileum

The specific site in the small intestine where bile salts are reabsorbed

Heterozygote Advantage

The theory that carrying one Cystic Fibrosis gene protected against cholera death

Nasopharynx

The area closed off by the soft palate during the swallowing reflex

Epiglottis

The structure that folds down to prevent food from entering the trachea during deglutition

Intrathoracic Pressure

The drop in this pressure during respiration can cause GERD if the LES is weak

H+/K+-ATPase

The apical "proton pump" responsible for moving hydrogen ions into the gastric lumen

Carbonic Anhydrase

The enzyme used to produce H+ and HCO3- from CO2 and water in parietal cells

Intestinal Phase

The phase of GI control initiated by chyme entering the duodenum