GI Physiology 4 Flashcards
Pancreatic secretions have what roles
Protective roles - HCO3 and mucus
Digestive roles - Enzymes
Cells of the pancreas include
Acinar cells
Duct cells
Goblet cells
Cells of the pancreas - Acinar cells
Protein synthesizing cell
Secretion of digestive enzymes
Secrete fluid
Cells of the pancreas - Duct cells
HCO3 secretion (important protective role)
Ion transport
Fluid transport
Cells of the pancreas - Goblet cells
Mucin secretion
- lubricates, hydrates, protects, and gives immune function
Pancreatic digestive enzymes - Inactive includes (one important one)
Trypsinogen
Pancreatic digestive enzymes - Active includes (4 important ones)
Alpha amylase
Lipase
Colipase
Trypsin inhibitor
Pancreatic digestive enzymes - Trypsinogen Function
INACTIVE
Functions in protein digestion
We do not want to initiate protein digestion in the pancreas (we want to wait until duodenum)
Pancreatic digestive enzymes - Alpha amylase Function
ACTIVE
Carb digestion
Pancreatic digestive enzymes - Lipase Function
ACTIVE
Lipid digestion
Pancreatic digestive enzymes - Colipase Function
ACTIVE
Lipid digestion
Pancreatic digestive enzymes - Trypsin Inhibitor
Inhibits trypsin
If we do not inhibit trypsin and protein digestion starts in pancreas, damage will occur
Stimulation of enzyme and fluid secretion - Key stimuli for secretion of fluid and enzymes
CCK and Ach
They promote Ca influx and promote docking of enzymes containing vesicles at the apical membrane
As you inc conc of CCK, you get inc in release of the enzymes
Multiple roles of CCK in the pancreas to include
CCK acts on the pancreas with reduces gastric emptying and stimulates acinar cells
Protection against and activation of digestive enzymes
Secretions of the pancreas can be very destructive so many of the digestive enzymes are inactive
Vesicles contain trypsin inhibitor
Low pH of vesicle prevents enzyme activation
How do we protect pancreas from its own secretions?
By making the proteases in the inactive form and keep the pH low in the vesicles
Trypsin inhibitor is there too just in case
Activation of enzymes in the____
DUODENUM
The on switch is located in the duodenum
When the enzymes empty into the duodenum, Entero Peptidase converts trypsinogen to trypsin and once you have a few molecules of trypsin they can go on to activate the other proteases
Duodenal Protection - Pancreas also functions to protect the
duodenum from the acid being emptied from the stomach to the duodenum
Duodenal protection - how does the pancreas protect it?
Acid come in, the duodenum senses it and releases secretin which stimulates the pancreatic ducts to release HCO3 which is important in protection
When you hear secretin think
GI PROTECTION
Duodenal protection - Negative regulation of acid secretion by secretin
Inc release of somatostatin
Dec gastrin secretion
Dec proton pump expression
Phase of pancreatic secretion - interdigestive - Pancreatic secretions during the interdigestive period parallel the _______
Therefore _____
Secretion is highest during ____
migrating motor complexes
Therefore, pancreatic secretions parallel motility
Secretion is highest during intestinal contractility
Phase of pancreatic secretion - interdigestive - Regulators of the cyclical pattern include
Stimulation by the PNS and CCK
Inhibition by alpha adrenergic input, somatostatin, and peptide YY (at the distal end of SI)
Phase of pancreatic secretion - interdigestive - During the “fed” state, there is a __ fold (inc/dec) in pancreatic secretions
5-20 fold INCREASE
