1. KIDNEYS
There are two kidneys (right & left) situated at back region. Its main function is to filter blood and throw away waste material in urine
Urine formed in kidneys get collected drop by drop fashion in a small bag (part of Kidney itself) called as Pelvis

2. URETERS
Urine collected in Pelvis gets drained by a urine pipe called as Ureters. Both Ureters (right and left) opens separately into bag like structure called as Bladder.

3. BLADDER
This is bag like structure which holds the urine. It is a flexible bag. It empties urine when we desire

4. URETHRA
It is a small tube like structure arising from bladder. It throws urine outside. It goes through penis in male and opens just in front of vagina in female.