ANATOMY

Detailed explanation-1: -One-dimensional, lubrication-theory analysis shows that peristalsis can pump urine from kidney into the bladder only at relatively low mean rates of urine flow. Under these circumstances isolated boluses of urine are propelled steadily through the ureter (assumed uniform) by the contraction waves.

Detailed explanation-2: -The renal pelvis narrows to become the ureter of each kidney. As urine passes through the ureter, it does not passively drain into the bladder but rather is propelled by waves of peristalsis.

Detailed explanation-3: -Urine drains from the renal pelvis of each kidney into the ureters. The ureters are long, thin tubes made of smooth muscle. Contractions of the smooth muscle push urine down through the ureters and into the bladder.

Detailed explanation-4: -As the urine is collected in the renal pelvis, the pelvic pressure increases and initiates a peristaltic contraction that is propagated along the ureter to the bladder. The peristaltic wave can move urine against an obstacle, with a pressure of up to 50–100 mm Hg.

Detailed explanation-5: -The ureters are bilateral thin (3 to 4 mm) tubular structures that connect the kidneys to the urinary bladder, transporting urine from the renal pelvis into the bladder. The muscular layers are responsible for the peristaltic activity that the ureter uses to move the urine from the kidneys to the bladder.