GIT- physiology

drnieves's version from 2017-06-11 19:58


Question Answer
GastrinG cells. Antrum, duodenum
GastrinIncrease H secretion, gastric mucosa, motility
Increase gastrinStomach distention, alkalinization, a.a, peptides, vagal stimulation Chronic atrophic gastritis Zollinger-Ellison syndrome PPI use
Decrease gastrinpH <1.5
SomatostatinD cells Pancreatic islets, GI mucosa
SomatostatinDecrease gastric acid, pepsinogen secretion, pancreatic and SI fluid secretion, gallbladder contraction, insulin and glucagon
Somatostatin increased byAcid
Somatostatin decrease byvagal stimulation
Analog of somatostatinOctrotide
OctreotideTx acromegaly, insulinoma, carcinoid syndrome, variceal bleeding
CCKI cells Duodenum
CCKIncrease pancreatic secretion (muscarinic), gallbladder contraction, sphincter of Oddi relaxation Decrease gastric empyting
CCK stimulationFA, a.a.
SecretinS cells Duodenum
SecretinIncrease pancreatic HCO3, bile secretion Decrease gastric acid
Secretin stimulationAcid, FA in dueodenum
Glucose dependent inusilinotropic peptide (GIP)K cells Duodenum, jejunum AKA. Gastric inhibitory peptide
Glucose dependent inusilinotropic peptide (GIP) exocrineDecrease H secretion
Glucose dependent inusilinotropic peptide (GIP) endocrineIncrease insulin release
Stimulation of glucose dependent inusilinotropic peptide (GIP)FA, a.a., oral glucose
Oral glucose loadLeads to increase insulin compared to IV due to GIP secretion
MotilinSI Produces migrating motor complexes
Motilin stimulationFasting state
Motilin R agonistsErythromycin Stimulate intestinal peristalsis
VIP (Vasoactive intestinal polypeptide)Parasympathetic ganglia in sphincters, gallbladder, SI
VIP (Vasoactive intestinal polypeptide)Increase water and electrolyte secretion, relaxation of sm and sphincters
VIP (Vasoactive intestinal polypeptide) stimulationDistention and vagal stimulation
VIP (Vasoactive intestinal polypeptide) inhibitionAdrenergic input
VIPomaNon a or B islet pancreatic tumor.
VIPomawatery diarrhea, hypokalemia, achlorydia
NOIncrease sm relaxation, including LES
Intrinsic factorParietal cells in stomach
Gastric acidParietal cells Decrease stomach pH
PepsinChief cells in stomach Protein digestion
HCO3Mucosal cells Stomach, duodenum, salivary glands, pancreas, brunner glands (duodenum) Neutralizes acid
IFVit B 12 binding protein (required for uptake in terminal ileum)
Gastric acid stimulationHistamine, ACh, gastrin
Gastric acid inhibitionSomatostatin, GIP, prostaglandin, secretin
Pepsin stimulationVagal stimulation, local acid
HCO3 stimulationPancreatic and biliary secretion with secretin
Pernicious anemiaAutoimmune destruction of parietal cells Chronic gastritis, anemia, Vit B12 decreased
GastrinomaGastrin secreting tumor High levels of acid ulcers refractory to PPI
HNeeded to convert pepsinogen into pepsin
a- amylaseStarch digestion. Active form
LipasesFat digestion
ProsteasesProtein digestion Trypsin, chymotrypsin, elastase, carboxypeptidases. Proenzyme (zymogen)
TrypsinogenConverted to trypsin by enterokinase/ enteropeptidase in duodenal/jejunal brush border
Absorbed by enterocytesMonosaccharides: glucose, galactose, fructose
SGLT1 (Na dependent)Take up glucose and galactose
GLUT 5Take up fructose by facilitated diffusion
D-oxylase absorption testDistinguishes GI mucosal damage from other malabsorption causes.
IronAbsorbed in duodenum
FolateAbsorbed in SI
B12Absorbed in terminal ileum with bile salts.
Peyer patchesUnencapsulated lymphoid tyssue in lamina propia and submucosa of ileum.
M cellsIn peyer patches (APC)
BileComposed of bile salts, phospholipids, cholesterol, bilirubin, water, and ions.
Rate limiting step of bileCholesterol 7a-hydrozylase
Bile functionsDigestion/absorption of lipids and fat soluble vitamins. Cholesterol excretion Antimicrobial (membrane disruption)
Direct bilirubinConjugated with glucuronic acid Water soluble
Indirect bilirubinUnconjugated Water insoluble
Heme oxygenaseMetabolize heme to biliverdin that then is reduced to bilirubin.
Unconjugated bilirubinremoved from blood by liver, conjugated with glucuronate, excreted in bile.
HistamineBinds H2. Increases cAMP
AchBinds M3.
Binds CCKB and stimulate ECLGastrin. Increase Ca