Pancreas

Question 1

Describe the inverse relationship of bicarbonate and chloride in pancreatic cells.

And how is it regulated?

Answer 1

Proton is pumped out into the serosal side via a H+/K+ ATPase that pumps proton out and potassium in.

Proton acts as a shuttle for bicarb in the serosal side to get into the cell and then out into the lumen.

The bicarb gets into the lumen via a sodium/bicarb antiport. (bicarb out, chloride in).

Then the chloride can get back out via the CFTR (which is why cystic fibrosis causes issues with pancreatic secretion)

Secretin: reacts the protons and stimulates Adenylcyclase which increases cAMP > increase PKA activity, phosphorylates CFTR, opening the pore for more chloride to go out. Increases the activity of H+/K+ ATPase via translocation.

CCK and Ach: augment the reaction by stimulating the potassium efflux channel into the serosal side which makes the inside of the cell more negative allowing for easier bicarb and chloride efflux.

Question 2

Some one is suffering from enterotoxins which constitutively activate the CFTR channel leading to massive loss of Cl, sodium, and water. How can you restore fluid balance

Answer 2

Give them a solution of glucose and salt.
Utilize the SGLT (sodium-glucose cotransporter) to bring both sodium and glucose back into the blood.

Chloride and water will passively follow

Question 3

What is dumping syndrome symptoms and pathophys?

Answer 3

Symptoms:
GI: watery, painless diarrhea, gassy
Systemic: weakness, diaphoresis, tachycardia

Pathophys:

• distention of lumen increases motility
• sudden rise in blood sugar increases insulin secretion which exacerbates tachycardia and diaphoresis (this is because the carbohydrates shoot into the small bowel
• there is a sudden increase of osmotic pressure (due to the enzymes and all that, which causes water to follow it)
• further distension
• the food gets barely digested and quickly moves to colon where bacteria produce alot of gas.
• loss of blood volume results in weakness and tachycardia.