Excretion is a process of filtering the unwanted substances from the body. Those substances are Carbon dioxide which excreted by lungs, Heat result of working metabolic excreted from the surface of the body (i.e. skin) and urine excreted by kidneys through bladder.

Role of Kidneys in Urinating Process: A pair of kidneys consist of millions of functional and blood in clearing wastes in very evident.The ureters (a duct) of both the kidneys drains into urinary bladder through urethra while empties by external urethral orifice. The job of the kidneys are to filter the unneeded and unwanted liquids from the blood. This lagged form consists of a toxin called nitrogen or urea.

Parts of a Kidney: 1 Cortex (outer layer) contains Nephron
2 Medulla (Inner part) reabsorbs the nutriens into blood.

After passing through the the kidneys, Urine keeps stored in bladder until the relaxing muscular.








http://www.marymount.k12.ny.us/maryn...ml/excretf.htm
http://en.wikipedia.org/wiki/Excretion
http://www.answers.com/library/World...Body-cid-28027