To review:
The relative medullary thickness (RMT) is a good predictor to determine an animal’s ability to produce concentrated urine or not, based on an RMT vs freezing point depression (FPD) plot.
Given:
The RMT and the FPD for different mammals are given in the Table 1:
Table 1: The RMT and FPD of different mammals.
Animal | RMT | FPD (ᵒC) |
Beaver | 1.3 | 0.96 |
Pig | 1.6 | 2 |
Human | 3 | 2.6 |
Dog | 4.3 | 4.85 |
Cat | 4.8 | 5.8 |
Lab rat | 5.8 | 4.85 |
Kangaroo rat | 8.5 | 10.4 |
Jerboa | 9.3 | 12 |
Sand rat | 10.7 | 9.2 |
Introduction:
RMT refers to the thickness of medulla of the kidney divided by volume (length X width X thickness) of the entire kidney. FPD is a test, which is used to measure the concentration of urine. It is known that fresh water freezes at 0°C, but the addition of solutes lowers this freezing temperature.
Explanation of Solution
The graph plot between RMT and FPD is given in the Figure 1.
Figure 1: Plot of RMT vs FPD.
It can be observed from the graph that as the RMT increases, the FPD also increases. This means that the concentration of the urine increases with an increase in relative length of loops of Henle. The graph follows an almost linearly increasing trend.
A slight deviation from the trend is observed in case of the laboratory rat and the sand rat.
Therefore, it can be concluded that the RMT is a good predictor of the ability of the mammal to produce concentrated urine.
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Chapter 51 Solutions
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