Reabsorption and Secretion

Question 1

How are substances reabsorbed?

Answer 1

Carrier mediated transport systems

Question 2

If carriers are at maximum transport capacity what happens to excess substrate?

Answer 2

Excreted in urine

Question 3

Where does sodium reabsorption occur?

Answer 3

Proximal tubule

Question 4

What does the rate of reabsorption of non actively reabsorbed solutes depend on?

Answer 4

Amount of water removed

Permeability of membrane to solute

Question 5

What is the normal value for ECF K+?

Answer 5

4mmoles/L

Question 6

What happens if K+ increases too much?

Answer 6

Hyperkalaemia, decreased resting membrane potential of excitable cells and eventually ventricular fibrillation and death

Question 7

What happens if K+ decreases too much?

Answer 7

Hypokalaemia, increases resting membrane potential of excitable cells, hyperpolarizes muscle and cardiac cells, cardiac arrhythmias, death

Question 8

How is K+ secretion regulated?

Answer 8

Aldosterone