Block 2 Lecture 24

Question 1

what happens in absorption

Answer 1

transcellular flux from apical to basolateral

Question 2

what happens in secretion

Answer 2

transcellular flux from basolateral to apical

Question 3

what does the transepithelial transport of glucose involve

Answer 3

1. Na glucose cotransporter in the luminal membrane
2. Na independent glucose transporter in the basolateral membrane
3. ATP dependent export of Na and import of K across the basolateral membrane

Question 4

what are some ways to mediate net OC+ secretion

Answer 4

1. Na,K - ATPase
2. OCT
3. OC+/H+ exchange
4. Na+/H+ exchange

Question 5

How does OC+ enter the cell

Answer 5

enters through OC+ transporter because facilitated diffusion us used and inside of the cell is negative

• OC+ is not favored to leave the cell because inside is negative so the OC+/H+ exchanger helps through secondary active transport
• to maintain the H+ gradient Na+/H+ exchanger permits Na+ to enter the cell and pump out the H+ that came in