Gastric Motility & Pancreatic Function Flashcards
Body of the stomach has
thin muscle wall - weak contraction
No mixing
Antrum of stomach has
thick muscle wall - powerful contraction
mixing, & forcing chyme into duodenum
What is chyme?
gastric content
What produces gastric peristaltic waves?
Peristaltic rhythm
Peristaltic rhythm
(~3/min) generated by pacemaker cells (longitudinal muscle layer)
slow wave rhythm =
basic electrical rhythm
slow waves -
spontaneous depolarisation/repolarisation
slow waves conducted through
gap junctions along longitudinal muscle layer
Slow wave depolarisation sub-threshold require further depolarisation to induce
action potentials for contraction
More AP waves means stronger
contraction
Gastrin & stretching of stomach walls increases
contraction
Fat/acid/increase tonicity in duodenum inhibits
motility
Bicarbonate secreted in submucosal gland of duodenum to
neutralise acid
Control of HCO3 secretion in duodenum:
- Vagus nerve & enteric nervous system
- S cells release secretin
what is secretin?
hormone that activates HCO3 release from pancreas & liver
3 parts of pancreas
Head
Endocrine part
Exocrine part
Head
Head (located within curvature of duodenum), body, tail (extends to spleen)
Endocrine part
islet of Langerhans, produce somatostatin (control of insulin and glucagon), glucagon and insulin
Exocrine part
acinar cells and lobules
Lobules connected by
intercalated ducts then intralobular ducts, and interlobular ducts before secreting into pancreatic duct, bile duct & through Sphincter of Oddi into duodenum
Sphincter of Oddi secrete
secrete enzymes and HCO3
Exocrine pancreas is responsible for
digestive function of pancreas
Functions of exocrine pancreas
Secretion of bicarbonate by duct cells
Secretion of digestive enzymes by acinar cells
Zymogens are
inactive form of enzyme
Acinar cells of pancreas contains
digestive enzymes stored as inactive zymogen granules
Zymogens prevents
autodigestion of pancreas
Enterokinase converts
trypsinogen to trypsin
Trypsin converts all other zymogens to
active forms
Types of pancreatic enzymes:
- Protease (peptide bonds)
- Nuclease (hydrolyse DNA/RNA)
- Elastase (collagen digestion)
- Phospholipase (phospholipids to fatty acids)
- Lipase (triglycerides to glycerol & fatty acids)
- α-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 acids in duodenum