The urinary tract is the set of organs whose role consists of the expulsion, following filtration, of liquid human waste in the form of urine. The urinary tract is made of the kidneys, ureters, bladder, urethra, and urinary meatus. Urine is made by the kidneys then transported by the ureters into the bladder where it is stored. Urination permits the evacuation of urine by passing through the urethra which ends with the urinary meatus. The urinary tract can be affected by infections called nephritis for the kidneys and urethritis for the ureters. Urine can also become infected at any time throughout the process. Cystitis is the infection of the urine in the final section of the urinary tract and if the infection makes its way up into the kidneys, it's then called pyelonephritis.