Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Pyelonephritis: Kidney Infection ?
    ### Response:
    The urinary tract is the bodys drainage system for removing wastes and extra water. The urinary tract includes two kidneys, two ureters, a bladder, and a urethra. The kidneys are two bean-shaped organs, each about the size of a fist. They are located near the middle of the back, just below the rib cage, one on each side of the spine.
    