About long kidney tubules......?

Question

Sorry i typed the wrong word. Why does man need a long kidney tubules?

Answer 1

I think you refer to long tubules in the nephrons of the kidney. The longer the tubes the more  re absorption of useful substances can take place before the content reach the calyx of the kidney.These useful things are glucose, water and amino acids.

Answer 2

The kidneys are responsible for maintaining electrolyte balance.  When blood passes through the capillaries in the glomerulus, urea, water, glucose, amino acids, vitamins, and small molecules are "forced" out of the blood stream by ultrafiltration mechanisms in Bowman's capsule.  The the rest of the nephron (renal tubule or "kidney tubule") is long so that it allows reabsorption of water, glucose, amino acids back into the bloodstream.  This happens by diffusion and by active transport and if we didn't have a long enough nephron then a lot of glucose, electrolytes, etc. wouldn't have time to be reabsorbed into the renal vein and carried back into the body, but would be lost into the urinary tract then into the bladder and then excreted.  So, we would have to take in more glucose, amino acids, etc. to compensate for the loss, if the nephron weren't long enough.