Renal system
Kidneys:
The functions of the kidneys are homeostasis - fluid balance, elimination, electrolyte balance, acid-base balance and endocrine function.
Kidneys - form and secrete urine.
Ureters - convey urine from the kidneys to the bladder.
Bladder - acts as a reservoir for the urine.
Urethra - allows urine to be expelled externally.