Reabsorption and secretion

Question 1

Describe the transport mechanisms in the kidney

Answer 1

Question 2

Describe the reabsorption of electrolytes in the proximal tubule

Answer 2

Question 3

Describe reabsorption of electrolytes in the ascending limb of the LoH

Answer 3

Question 4

Describe the reabsorption of electrolytes in the distal tubule

Answer 4

5% Na+ and Cl- absorbeed via co-transport

Question 5

Describe the movement of electrolytes in the collecting duct

Answer 5

Question 6

What is the effect of aldosterone on potassium in the collecting duct?

Answer 6

K+ secretion via principle cells
Increased activity of Na+/K+ pump - resorbs Na, secretes K
Increased number of K+ channels

Question 7

Describe the effect of insulin on potassium

Answer 7

Used to shift K+ into cells
Increases activity of Na+/K+ pump
Can be used to treat hyperkalaemia

Question 8

Describe the passage of Ca through the kidney

Answer 8

Free ion - freely filtered
Passive reabsorption in proximal tubules and ascending limb of LoH - driven by Na+
Active transcellular reabsorption in distal tubules
PTH (parathyroid hormone) can increase Ca2+ reabsorption

Question 9

Describe the passage of phosphate in the kidney

Answer 9

Free ion - freely filtered
80% reabsorbed in proximal tubules
Transcellular process: co-transport with Na+ ions
PTH decreased phosphate reabsorption

Question 10

Describe the passage of magnesium in the kidney

Answer 10

Free ion - freely filtered
30% reabsorbed in proximal tubules - paracellular movement driven by Na+
65% reabsorbed in thick ascending limb of LoH due to transepithelial potential
5% reabsorbed in distal tubules via Mg ATPases
Regulated via PTH

Question 11

Describe the passage of glucose in the kidney

Answer 11

Freely filtered
Only reabsorbed in proximal tubule via secondary active reabsorption
As glucose conc increases more of the proximal tubule participates in reabsorption