MICROANATOMY

Detailed explanation-1: -Urine is moved through the ureters in peristaltic waves. Calmodulin activates myosin light-chain kinase in ureteral smooth muscle, causing contraction and electrical pacemaker cells in the proximal renal pelvis, controlling the frequency of these waves (in humans 1–6 waves per minute).

Detailed explanation-2: -As urine passes through the ureter, it does not passively drain into the bladder but rather is propelled by waves of peristalsis. The ureters are approximately 30 cm long. The muscular layer of the ureter creates the peristaltic contractions to move the urine into the bladder without the aid of gravity.

Detailed explanation-3: -Ureteral peristalsis can be considered as a series of compressive zones, corresponding to waves of active muscular contraction, that move at near-constant speed along the ureter towards the bladder.