Use the mouse to highlight the answers. They are written in white
| Question |
Answer |
Link |
| Which of the three limbs has active transport? |
The thick ascending limb |
Link |
| What system of reabsorption is used in the loop of henle? |
Countercurrent multiplier |
Link |
| Explain how the countercurrent multiplier works? |
- "Descending limb is permeable to water but not solutes"
- "The thick ascending loop is not permeable to water but solutes are pumped out"
- "Therefore, osmolarity of peritubular space is elevated, which draws water out of the descending limb"
- "Therefore, solute concentration of the fluid in the ascending limb is higher... causing more pumping"
- "Therefore, osmolarity of peritubular space is elevated, which draws more water out of descending limb"
Courtesy of Dr Ali Mobasheri (University of Nottingham School of Veterinary Medicine and Science) |
Link |
| What happens to the concentration of the tubular fluid as it passes around the loop? |
The concentration increases as it descends as water leaves the tubule. However as the fluid ascends the other side ions are transported out causing the concentration to decrease. By the end of the loop the concentration is the same as at the start but the volume is greatly reduced. |
Link |
| Why is the gradient within the medulla not removed by the vasa recta? |
It is also set up as a countercurrent system. Lots of ions enter as it passes down the medulla and the interstitium become more concentrated but these all leave as it rises back out of the medulla and the interstitium becomes less so. |
Link |
