How do collecting tubules carry urine toward the renal pelvis?

Collecting tubules transport urine from the nephrons in the kidney cortex toward the renal pelvis through a structured drainage system.12

As these tubules travel through the renal medulla, they converge into larger ducts, eventually forming the ducts of Bellini. These ducts discharge urine through openings on the surface of the renal papilla, which is the apex of a renal pyramid.134

Once discharged, the urine enters the minor calyces. From there, it moves into the major calyces and finally into the renal pelvis. The movement of urine through the calyces and into the renal pelvis is facilitated by hydrostatic pressure and peristaltic waves of contraction originating in the muscle fibers of the minor calyces. Gravity also assists this downward flow toward the ureter and urinary bladder.513