Question

what is the importance having a long loop of henle and short loop of henle in a nephron

Answer 1

Hlo Here is ur answer....
Loop of Henle, long, U-shaped portion of the tubule that conducts urine within each nephron of the kidney of reptiles, birds, and mammals.
The principal function of the loop of Henle appears to be the recovery of water and sodium chloride from the urine.....
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Answer 2

Henle's loop is involved in the concentration of urine that is its main purpose is to absorb water. Various animals have various types of excretory products. These excretory products may contain ammonia, urea, uric acid.  Of which ammonia is the most toxic.  So it needs more water for its elimination where's urea is least toxic and so it needs less water for it's elimination.  Humans are ureotelic so the long loops of Henley makes the urine more concentrated by absorbing more water. While in fishes since its excretory product is ammonia it needs to be more diluted in order to reduce it's toxicity