Kidneys and Concentrated Urine
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The camel's kidney functions in a similar way as does the kidney of the kangaroo rat. As a desert rodent, the kangaroo rat rarely ever drinks any water as it gains water from the dry food that it eats (10). Consequently the rodent can produce a urine that is twice as concentrated as sea water (6). In a similar way, dehydrated camels exposed to the hot conditions of the desert have the ability to conserve water by concentrating the urine. Although the camel does not produce a urine as concentrated as the kangaroo rat, the urine concentration of a camel can become significantly greater than sea water (6) . Besides retaining more water, a concentrated salt level in the urine allows the camel to drink salty waters (6) which opens up the desert environment. For example, camels have been known to eat succulent plants in places where a river bed has dried up, and usually these plants contain a high concentration of salt (6). Abdalla (1979) investigated the structure of the camelian kidney to discover whether or not the anatomical features necessary for producing a highly concentrated urine were present or not. By analyzing the length of the loop of Henle and the structure of the renal medulla in a kidney, one is able to determine how effective the animal is at producing a concentrated urine (7). The relative thickness of the medulla was calculated in the camelian kidney as it has been demonstrated that this thickness has a direct relationship with the ability to produce a highly concentrated urine (7). A relative thickness of the medulla is a good measure of the length of the loop of Henle which is an indicator of urine concentration (7). The thickness reported in camels was 7.89 in comparison to the value of 8.5 in kangaroo rats (7). A ratio of medullary to cortical thickness in the kangaroo rat was known to be 5:1, and Abdalla discovered that camels compares similarly with a ratio of 4:1. Abdalla (1979) concluded from his findings and comparisons with other mammals that the camelian kidney did in fact have the anatomical features necessary in producing a concentrated urine (7). Etzion and Yagil (1986) investigated the kidney of the camel following rapid rehydration. A dehydrated camel can replace water within minutes of drinking (11), and some of this water is quickly absorbed into the bloodstream. With water in the bloodstream, ADH declines and the kidney will return to normal renal function within 30 minutes of drinking (11). A concentrated urine with a syrupy consistency was noted to change to a watery and colorless urine after only a short time of drinking (11). Etzion and Yagil (1986) concluded that the camel was not only adapted well in retaining water, but also with its ability to rapidly restore renal function as well as some other body functions (11). |
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