Pancreatic secretion: Johnson

Question 1

Describe the two components of pancreatic exocrine secretion, cells of origin, and function.

Answer 1

::Aqueous component:: basically HCO3-
Function- neutralize gastric acid secretions. Responsible for neutralizing gastric acid entering duodenum.
Stimulated by- secretin–> cAMP —> upreg of bicarb/Cl- channels
Cells of origin- ductule cells

::Enzymatic component:: (amylase, lipase, protease)
Function- digestion of all food
Stimulated by- CCK—> Acetylcholine and vagus–> Ach
Cells of origin- acinar cells

Question 2

Understand the formation of both the aqueous and enzymatic components of pancreatic secretion.

Answer 2

::Aqueous::
Na+/K+ATPase exchanges Na+ (out) for K+ (in). Na+ re-enters the cell down its concentration gradient and is exchanged for H+ (out). Carbonic anhydrase converts H2O—> OH-, which combines with CO2 (diffuses in) to form HCO3-, which is pumped out of the cell in exchange for Cl-.

::Enzymatic::
Protein foundation for enzyme synth. on RER. First part synth. is lipophilic. This allows protein to transverse membrane and be inside the membrane until released. This keeps the assembled enzyme from degrading cell. Condensing vacuoles of golgi concentrate enzyme until they become a mature zymogen granule. They then await stimulus (CCK or Ach) to be released.

Question 3

Explain the regulation of pancreatic secretion

Answer 3

As with gastric secretion, initial spike (15-20% of maximal pancreatic response) in pancreatic secretion (ENZYME ONLY) is due to smell, taste, and thought of a meal aka cephalic phase (vagus n.)
No sign. rise in bicarb from sham feeding.
Pancreatic secretion continues until meal is fully digested (can take 6-7 hrs)
Food filling the intestine (intestinal phase) is what accounts for 70-80% of maximal pancreatic response. Stimulated by secretin release.

Question 4

Discuss the basis for potentiation and its importance in the pancreatic response to a meal.

Answer 4

Ach potentiates effect of secretin on ductule cells, allowing for maximum secretion.

Question 5

Discuss pancreatitis and its causes as well as clinical conditions arising from decreased secretion of pancreatic juice.

Answer 5

Major cause of pancreatic insufficiency is pancreatitis (PT).
Most PT due to obstruction of pancreatic duct (gallstones or alcoholism 90%)—> enzymes back up into pancreas and digest parenchyma of pancreas.
PT can lead to decr. secretion of enzymes and HCO3-.

Kwashiorkor can lead to pancr. insuff. bc you don’t get enough protein in your diet to synth. proteins. No lipase–> fatty shits (steatorrhea).

Cystic fibrosis = no Cl- transporter or shitty transporter–> mucus secretion–> blocks ducts—> PT–> decr. bicarb, volume, enzymes–> fatty shits