gastric motility and pancreatic function Flashcards
where does the majority of mixing occur in the stomach ?
antrum due to thick muscle creating a powerful contraction
causes mixing, contraction of pyloric sphincter to prevent emptying of gastric content until fully mixed
what cells produce peristaltic rhythm and at what w/min ?
pacemaker cells in the longtidudinal layer of the muscle
3/min
how are slow waves conducted through the gastric cells in the stomach ?
gap junctions along longitudinal muscle
what determines the strength of peristaltic contraction ?
number of Aps/Waves
what inhibits motility of gastric material ?
fats/amino acids/hypertonicity in the duodenum
what factors increase peristaltic contraction ?
gastrin
distension of the stomach wall
what do brunners glands secrete ?
bicarbonate (stimulated by secretin)
what does acid in the duodenum do ?
1- long/short reflexes cause HCO3 secretion
2- release of secretin from S cells cause HCO3 secretion
3- acid neutralisation then inhibits secretin release (negative feedback)
what are the three main parts of the pancreas ?
head,tail,body
describe the endocrine portion of the pancreas
pancreatic islets of langerhans contain islet cells
- beta islet cells produce insulin and the alpha islet cells produce glucagon
- it also produces somatostatin which controls the secertion of insulin and glucagon
describe the exocrine portion of the pancreas
lobules of acinar cells are connected by intercalated ducts
these become intralobular ducts
become interlobular ducts
these become the main pancreatic duct which joins with the common bile duct at the hepatopancreatic ampulla
what cells in the pancreas secrete bicarbonate ?
duct cells
which cells in the pancreas secrete digestive enzymes ?
acinar cells
what converts zymogens to their active state ?
enterokinase converst tripsinogen to tripsin
tripsin converts zymogens to their active form
what is zymogen secretion stimulated by ?
CKK that is released in response to fat/amino acids in the duodenum
