Gastric Motility and Pancreatic Function Flashcards
What is the effect of peristaltic waves on the body of the stomach?
Weak contraction (no mixing)
What is the effect of peristaltic waves on the antrum?
Powerful contraction
Mixing
Contraction of the pyloric sphincter
What is the purpose of contracting the pyloric sphincter?
Small amount of chyme entering duodenum
Most of antral contents moved backwards
What is the rate of peristaltic rhythm?
3/min
Pacemaker cells of peristaltic rhythm are situated where?
Longitudinal muscle layer of muscularis externa
What is the Basic electrical rhythm of the gastric system?
Spontaneous slow wave depolarisation through gap junctions
Number of Action potentials determines what?
Contraction STRENGTH
What is the effect of gastrin on the peristaltic waves?
Stronger contractions
Distension of the stomach wall causes what?
Long reflexes (vagus nerve) Short reflexes (ENS)
Distension reflexes have what effect?
Increased contraction
What is the effect of food particles in the duodenum?
Mobility inhibition
How is acid neutralised in the duodenum?
Secretion of Bicarbonate (HCO3)
Where is Bicarbonate secreted from in the duodenum?
Brunner’s Gland duct cells
Why does the oesophagus produce bicarbonate?
Increase the speed of food passage
Acid and Bicarbonate forms what?
H2CO3
–> H20 + CO2
Acid in the duodenum triggers what?
Long and short reflexes for HCO3 secretion
Release of secretin for HCO3 secretion
Secretin release triggers what?
HCO3 secretion from pancreas and liver
How is secretin release inhibited?
Acid neutralisation
Islet cells of the pancreas produce what?
(Endocrine)
Insulin
Glucagon
Somatostatin
The exocrine pancreas produces what?
Bicarbonate
Digestive Enzymes
What is the sequence followed leaving the acini cells of the pancreas?
Acini cell
Intercalated duct
Intralobular duct
Interlobular duct
Bicarbonate is produced by what in the pancreas?
Duct cells
Digestive enzymes are produced by what in the pancreas?
Acinar cells
The pancreatic duct meets the duodenum where?
Sphincter of oddi
+ accessory duct
What are Zymogens?
Inactive forms of digestive enzymes
Why does the pancreas store digestive enzymes as zymogens?
Prevention of autodigestion
How are Zymogens activated?
Contact with enterokinase on brush border membrane
Enterokinase converts what?
Trypsinogen to trypsin
What is the role of trypsin?
Converts all other zymogens into their active form
Enterokinase is presented where?
Brush border of duodenal enterocytes
What are the categories of pancreatic enzymes?
Proteases, nucleases, Elastases, Phospholipases, Lipases, a-amylase
What is the role of nucleases?
Hydrolise DNA/RNA
What is the role of elastases?
Digest collagen
What is the role of phospholipase?
Convert phospholipids to FAs
What is the role of lipases?
Convert TAGs to FAs+Glycerol
What stimulates the secretion of bicarbonate in the pancreas?
Secretin in response to acid in duodenum
What stimulates the secretion of zymogen from the pancreas?
Cholecystokinin (CCK) release in response to Fat/AAs in duodenum
Organic nutrients in the duodenum trigger what?
Neural/reflex triggering pancreatic function
