Secretions

Question 1

What would omeprazole do to gastric secretions?

Answer 1

Omeprazole is a proton pump inhibitor. In parietal cells…

Increased metabolism and water leads to production of bicarbonate and proton. Proton is pumped into the lumen with ATPase.

Bicarb efflux into portal vein is exchanged for chloride influx. Subsequently the chloride follows proton into lumen.

A proton inhibitor will increase pH in lumen but also decrease pH in portal vein (alkaline tide)

Question 2

What are the ionic properties of pancreatic juice

Answer 2

Always isotonic.

There is isotonic sodium and potassium. The only thing to look at really is bicarb and chloride and since the two are exchanged in pancreatic secretion. There is an inverse relationship

HIGH bicarbonate.
LOW chloride.

There is also K+/H+ ATPase which excretes proton to the serosal side, acting as like a shuttle to bring more bicarb in.

Secretin increases activity of CFTR and K+/H+ ATPase.

CCK potentiates this action by stimulating potassium efflux into the serosal side, making the intracellular conditions more negative.

Question 3

Describe secretions in the small intestine

Answer 3

Duodenum is similar to pancreas in that it has a chloride, bicarbonate exchanger. Chlorine is brought into the cell and bicarbonate is effluxed.

Also has CFTR channel (easily mutated or messed with)

Instead of a potassium/proton ATPase, there is a sodium, proton exchanger.

Jejunum has no bicarb stuff, only CFTR and some other ion shit.

CFTR is responsible for chloride, sodium, and water loss.