Structure
The urinary system refers to structures which conduct urine, formed in the nephrons of the kidney, to the point of its excretion. There are two kidneys in the human body, on the right and the left. Urine begins to be created within a nephron, which is a small unit within the kidney. It travels through the structures of the nephron and into the collecting duct system, which is a system of larger vessels within the kidney. The collecting ducts join together to form minor calyces and ultimately major calyces, larger and larger ducts. These drain into a structure called the pelvis of the kidney, and enter the ureter. The ureter is a tube-like structure which carries the urine from the kidneys to the bladder. The ureters enter the bladder from within the bladder.
Urine collected in the bladder is discharged through the urethra, which ends at the external urethral orifice.