Describe how mammalian kidneys work.

In the convoluted tubules, a filtration process is carried out, then blood plasma is filtered into the renal tubules, thereby forming primary urine. In the renal tubules of which the knees are composed, water, sugar and amino acids are reabsorbed from the primary urine, thereby forming secondary urine. It enters the cerebral urine. tubules thereby forming the medulla. The end product of protein metabolism is urea. Further, urea is sent to the ureters, then to the bladder, and then through the urethra is excreted from the body.