Gastric Motility and Pancreatic Function Flashcards
where do the peristaltic waves of the stomach go?
body to antrum
what is significant at the fact that the body of the stomach has weak muscle?
weak contrcation means no mixing
does the antrum have weak or thick muscle? what does this mean?
Thick muscle = powerful contraction
Mixing
Contraction of pyloric sphincter
Only small quantity of gastric content (chyme) entering duodenum
Further mixing as antral contents forced back towards body
what is the peristaltic rhythm generated by?
pacemaker cells (longitudinal muscle layer)
what produces a slow wave?
spontaneous depolarisation/repolarisation
what determines the strength of contraction of waves?
number of APs
does gastrin increase or decrease contraction?
increase
does dilation of stomach wall decrease or increase contraction?
increase
how does fat/acid/amino acid/hypertonicity in duodenum effect motility?
inhibits
where is HCO3 secreted from in the duodenum?
brunners gland duct cells (submucosal glands)
acid in duodenum triggers…
Long (vagal) & short (ENS) reflexes HCO3 secretion
Release of secretin from S cells HCO3 secretion
- Secretin HCO3 secretion from pancreas & liver
- Acid neutralisation inhibits secretin release (negative feedback control)
what are the three parts of the pancreas?
body, tail, head
what is involved in the endocrine portion of the pancreas?
pancreatic islets (islets of Langerhans):
islet cells produce insulin, glucagon (control [glucose]blood ) and somatostatin (controls secretion of insulin and glucagon)
what is involved in the exocrine portion of the pancreas?
acinar cells lobules
what are lobules connected by?
intercalated ducts
where does the secretion of bicarbonate occur?
duct cells
where does the secretion of digestive enzymes occur?
acinar cells
what do acinar cells contain?
digestive enzymes stored as inactive zymogen granules
what is the function of zymogens?
prevents autodigestion of pancreas
what converts trypsinogen to trypsin?
enterokinase
what converts all other zymogens to active forms?
trypsin
what are the categories of pancreatic enzymes?
proteases nucleases elastases phospholipases lipases a amylase
what is the function of proteases?
Cleave peptide bonds
what is the function of nucleases?
Hydrolyse DNA/RNA
what is the function of elastases?
Collagen digestion
what is the function of phospholipases?
Phospholipids to fatty acids
what is the function of lipase?
Triglycerides to fatty acids+ glycerol
what is the function of a amylase?
Starch to maltose + glucose
bicarbonate secretion stimulated by
secretin
secretin released in response to
acid in duodenum
zymogen secretion stimulated by
cholecystokinin (CCK)
CCK released in response to
fat / amino acid in duodenum
