Section 7: Pancreatic Secretion, Biliary Secretion, and Gall Bladder Function Flashcards
The common bile duct joins:
Cystic duct and common hepatic duct
Secretory unit of the pancreasL
Lobule
What connect the main pancreatic duct and the lobules?
interlobular ducts
Components of the lobules:
intercalated ducts that each end in an acinus
Main components of he pancreatic acinar cells:
Zymogen granules, golgi, mitochondria and RER
Functions of the pancreas:
insulin/ glucagon release, secretion of digestive enzymes and HCO3- rich fluid
What is the exocrine function of the pancreas?
secretion into ducts of digestive enzymes and HCO3- rich fluid
To where is the fluid carrying enzymes from the pancreas carried?
duodenum
Effect of acid on digestive enzymes:
inactivation
Aqueous component of pancreatic juice:
basal spontaneous secretions, secretin-stimulated secretions (higher HCO-2), and Cl-/ HCO3- exchange
Fluid flow from the pancreas:
acinar fluid, to intralobular ductal system, to extralobular ductal system, to main collecting duct
Components of secretin-stimulated secretions, highest concentration to lowest concentration:
Na+, HCO3-, Cl=, K+ (155mM, 115, 40, and 7mm)
What causes the secretion of fluids from the pancreas?
secretin injection or acid meal in the duodenum
General effect on ion concentrations as section rate increases from the pancreas:
Na+ and K+ remain the same, Cl- decreases, and HCO3- increases
pH in the duodenum with and without secretions from the pancreas:
7.8 without, 8.3 with
Basal primary secretions from the pancreas are ____-like.
plasma
What makes the transepithelial voltage more lumen-negative and is the driving force for Na+ to enter the lumen via tight junctions?
the movement of Cl- into the lumen of the acinus
What transporter produces the net Cl- uptake in the pancreas acinar cells?
Na/K/Cl contransporter, driven by the Na gradient created by the Na/K pump
What drives he Na/K/Cl cotransporter?
the Na gradient created by the Na/K pump
What pumps cause a rise in intracellular stores of K?
Na/K pump and the Na/K/Cl cotransporter
What neurotransmitter is a potent stimulator of Cl- secretion?
acetylcholine (cholinergic)
What does the intracellular accumulation of Cl- drive?
Cl- secretion into the acinar lumen through apical-membranes Cl- channels
Through what mechanisms does bicarbonate get secreted into the lumen of the duct?
Cl-HCO3- exchange mechanism
True or False? HCO3- can enter the lumen directly.
T. across the basolateral membranes via an Na/HCO3 cotransporter
What is the splitting of water to get the OH- needed for CA driven by?
The extrusion of H+ be an N-H exchanger
In which directions are the net movements of ions and water when extra lobular duct cell secretion is stimulated?
Na+, HCO3-, water into the lumen, H+ into the interstitial space
What is the most powerful stimulus for HCO3- secretion?
secretin
What does secretin activate in the extralobular duct cell?
adenylyl cyclase
Action of adenylyl cyclase in the extralobular duct cell:
raise [cAMP]
Action of cAMP in the extralobular duct cell:
stimulates protein kinase A and the phosphorylation of CFTR
True or False? The movement of H+ and HCO3- in the extralobular duct cells is in the same direction as in the stomach.
F. opposite
True or False? The interstitial-negative voltage pulls Na+ into the interstitial space via tight junctions
F. lumen-negative
What does Acetylcholine in the extralobular duct cells stimulate?
HCO3- secretion and activation of Gq
Functions of Gq in the extralobular duct cells:
sitmulates PLC to release DAG and IP3
Functions of DAG in the extralobular duct cells:
stimulates PKC
Functions of PI3 in the extralobular duct cells:
release of Ca2+ from internal stores
