RLO: The Anatomy of the Kidneys


The Passage of Urine

Urine formed in each nephron drains down the collecting ducts and into the renal pelvis.

Urine exits the kidneys via the right and left ureters, which deliver urine to the bladder by peristaltic contractions of their muscle walls, and also by gravity.

As the bladder fills with urine, its walls expand. When it is full, reflexes are stimulated which lead to micturition, or going for a wee. Urine is expelled through a small tube called the urethra which leads to the exterior of the body.